Engine Controls - 3.4l - DTC p0220 to DTC p0455 Chevrolet Equinox I

Circuit Description

The throttle body assembly contains the following components

1. The throttle blade
2. The throttle actuator motor
3. The throttle position (TP) sensor 1 and 2
4. The throttle actuator control (TAC) module

The TAC system monitors the throttle position with 2 sensors. If the powertrain control module (PCM) receives a message from the TAC module that indicates TP sensor 2 voltage is outside a predetermined range, the reference voltage is out of range, or an improper throttle blade minimum position was learned, DTC P0220 will set.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC P0220 Throttle Position (TP) Sensor 2 Circuit

Conditions for Running the DTC

1. DTCs P0606, P2107, P2108 are not set.
2. The ignition switch is in the crank or the run position.
3. The Ignition 1 Signal parameter is more than 5.23 volts.
4. The communications between the TAC module and the PCM must be valid.

Conditions for Setting the DTC

1. The TP sensor 2 voltage is less than 0.282 volts or more than 4.6 volts for longer than 100 ms. This test occurs continuously. OR
2. The PCM learns a minimum throttle position of less than 0.282 volts or more than 0.813 volts. This test occurs once per ignition cycle at power-up. OR
3. The TP sensor reference voltage is between 4.54-5.21 volts for longer than 10 ms. This test runs continuously.

Action Taken When the DTC Sets

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
3. The control module commands the TAC system to operate in the Reduced Engine Power mode.
4. A message center or an indicator displays Reduced Engine Power.
5. Under certain conditions the control module commands the engine OFF.

Conditions for Clearing the MIL/DTC

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

DTC P0220

The powertrain control module (PCM) provides ignition positive voltage to the coil side of the fuel pump relay. When the ignition switch is first turned ON, the PCM energizes the fuel pump relay, which applies power to the fuel pump. The PCM enables the fuel pump relay as long as the engine is cranking or running, and crankshaft reference pulses are received. If no crankshaft reference pulses are received, the PCM de-energizes the fuel pump relay after 2 seconds. The PCM monitors the voltage on the fuel pump relay control circuit. If the PCM detects an incorrect voltage on the fuel pump relay control circuit, DTC P0230 sets.

DTC Descriptors

This diagnostic procedure supports the following DTC

DTC P0230 Fuel Pump Relay Control Circuit

1. The ignition is ON.
2. The system voltage is between 9-18 volts.

1. The PCM detects an incorrect voltage on the control circuit of the fuel pump relay.
2. The condition exists for less than 1 second.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 4: This step verifies that the PCM is providing voltage to the fuel pump relay.
2. 5: This step tests for an open in the ground circuit to the fuel pump relay.
3. 6: This step tests if voltage is constantly being applied to the control circuit of the fuel pump relay.

DTC P0230

System Description

The powertrain control module (PCM) uses information from the ignition control (IC) module and the camshaft position (CMP) sensor in order to determine when an engine misfire is occurring. By monitoring variations in the crankshaft rotation speed for each cylinder, the PCM is able to detect individual misfire events. A misfire rate that is high enough can cause the 3-way catalytic converter (TWC) to overheat under certain driving conditions. The malfunction indicator lamp (MIL) will flash ON and OFF when the conditions for TWC overheating are present. If the PCM detects a misfire rate sufficient to cause emission levels to exceed mandated standards, DTC P0300 sets.

This diagnostic procedure supports the following DTC

DTC P0300 Engine Misfire Detected

1. DTC P0016, P0101, P0102, P0103, P0107, P0108, P0116, P0117, P0118, P0120, P0125, P0128, P0220, P0315, P0335, P0336, P0340, P0341, P0608, P1125, P1516, P2101, P2108, P2120, P2125, P2135, or P2138 is not set.
2. The engine speed is between 525-5,700 RPM.
3. The ignition voltage is between 9-18 volts.
4. The engine coolant temperature (ECT) is between -7 and +123°C (19-253°F).
5. If the ECT is less than -7°C (19°F) at engine start-up, the diagnostic will be disabled until the ECT is more than 21°C (69°F).
6. The fuel level is more than 10 percent.
7. The antilock brake system (ABS) and the traction control system are not active.
8. The transmission is not changing gears.
9. The PCM is not in fuel shut-off or decel fuel cut-off mode.
10. The PCM is not receiving a rough road signal.
11. The power management is not active.
12. Excessive drive wheel slip is not detected.

The PCM is detecting a crankshaft rotation speed variation indicating a misfire sufficient to cause emission levels to exceed mandated standards.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

1. Excessive vibration from sources other than the engine could cause DTC P0300 to set. The following are possible sources of vibration: Variable thickness brake rotors-Refer to «Symptoms - Hydraulic Brakes»(/chevrolet/equinox/i-2004-2009/remont/mechanical-hydraulic/#hydraulic-brake-system__symptoms-hydraulic-brakes) . Worn or damaged accessory drive belt-Refer to «Symptoms - Engine Mechanical»(ref-239708-S29155610042006080100000) .
2. Spray water on the secondary ignition components using a spray bottle. Look and listen for arcing or misfiring.

If condition is intermittent or not active, refer to Testing for Intermittent Conditions and Poor Connections .

The number below refers to the step number on the diagnostic table.

1. 2: If the actual crankshaft position (CKP) variation values are not within the learned values, the misfire counters may increment.

DTC P0300

The crankshaft position (CKP) system variation learn feature is used to calculate reference period errors caused by slight tolerance variations in the crankshaft, and the crankshaft position sensors. The calculated error allows the powertrain control module (PCM) to accurately compensate for reference period variations. This enhances the ability of the PCM to detect misfire events over a wider range of engine speed and load.

The CKP system variation compensating values are stored in PCM memory after a learn procedure has been performed. If the actual CKP variation is not within the CKP system variation compensating values stored in the PCM, DTC P0300 may set.

If the CKP system variation values are not stored in the PCM memory, DTC P0315 sets.

This diagnostic procedure supports the following DTC

DTC P0315 Crankshaft Position (CKP) System Variation Not Learned

The diagnostic runs continuously.

The PCM detects that the CKP system variation values are not stored in memory.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

DTC P0315

Diagnostic Fault Information

DTC P0325, P0326, P0327, or P0332

Typical Scan Tool Data

Spark

Circuit/System Description

The Knock Sensor (KS) System enables the powertrain control module (PCM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The sensors are located below each cylinder head on the engine block. The KS produces an AC voltage signal that varies depending on the vibration level during engine operation. The PCM adjusts the spark timing based on the amplitude and the frequency of the KS signal. The PCM receives the KS signal through a signal circuit. The KS ground is supplied by the PCM through a low reference circuit. The PCM learns a minimum KS noise level at idle and uses calibrated values for the rest of the RPM range. The PCM should monitor a normal KS signal within the noise channel. If the PCM malfunctions in a manner that will not allow proper diagnosis of the KS system, DTC P0325 sets. If the PCM detects the KS signal outside of the noise channel, or the KS signal is not present. DTC P0327 refers to the bank 1 KS and DTC P0332 refers to the bank 2 KS.

1. DTC P0016, P0101, P0102, P0103, P0116, P0117, P0118, P0120, P0125, P0128, P0220, P0335, P0336, P0340, P0341, P0608, P1125, P1516, P2101, P2108, P2120, P2125, P2135, or P2138 is not set.
2. The engine speed is between 1,000-5,000 RPM.
3. The throttle position (TP) indicated angle is more than 10 percent.
4. The engine load is more than 40 percent.
5. The engine coolant temperature (ECT) is more than 60°C (140°F).
6. The knock retard is less than 15 degrees.
7. The ignition 1 signal is more than 9 volts.
8. The engine run time is more than 30 seconds.
9. DTC P0325, P0327 and P0332 run continuously once the above conditions are met.

P0325

The PCM detects a malfunction in the KS diagnostic circuitry that will not allow proper diagnosis of the KS system.

P0327 or P0332

The KS signal is outside of the assigned noise channel or the KS signal is not present for more than 0.5 second.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. Inspect the KS for physical damage. A KS that is dropped or damaged may cause a DTC to set.
2. Inspect the KS for proper installation. A KS that is loose or over torqued may cause a DTC to set. The KS should be free of thread sealant. The KS mounting surface should be free of burrs, casting flash, and foreign material.
3. The KS must be clear of hoses, brackets, and engine electrical wiring.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

1. «Engine Controls Connector End Views»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__engine-controls-connector-end-views)
2. «Powertrain Control Module (PCM) Connector End Views»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__powertrain-control-module-pcm-connector-end)

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__circuit-testing)
2. «Connector Repairs»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__wiring-repairs)

Circuit/System Testing

1. Test for an intermittent and for a poor connection at the affected knock sensor (KS).
2. With the ignition OFF, disconnect the affected knock sensor.
3. With the ignition OFF, Measure the resistance for infinite ohms from the sensor signal terminal on the knock sensor to a good ground, and the low reference terminal on the knock sensor to a good ground with a DMM. If resistance does not measure infinite ohms at both terminals than replace the affected KS.
4. Connect the DMM between the terminals of the affected KS. Set the DMM to the 400 Hz scale, let stabilize at 0 Hz. Tap on engine block with a non-metallic object near the affected KS while observing the signal indicated on the DMM. If the DMM does not display a fluctuating frequency while tapping on the engine block then replace the affected KS.
5. Turn the ignition ON, engine OFF. Set the DMM to the DC voltage scale. Measure for 4.2 volts from the KS signal circuit to a good ground, and the KS low reference circuit to a good ground with the DMM. If over 4.2 volts with the ignition OFF disconnect the PCM and test the KS signal circuit or the KS low reference circuit for a short to voltage. If under 4.2 volts with the ignition OFF disconnect the PCM test the KS signal circuit or the KS low reference circuit for an open, short to ground, or high resistance.
6. Test for intermittent or poor connections at the PCM.
7. If all circuits test normal then replace the PCM.

Repair Procedures

1. «Control Module References»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__control-module-references) for ECM replacement, setup, and programming.
2. «Knock Sensor (KS) Replacement»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2)

The crankshaft position (CKP) sensor is a 24X sensor. It provides 24 digital ON/OFF signals to the powertrain control module (PCM) per revolution of the crankshaft. This information is used by the PCM for ignition timing, fuel injector timing, misfire diagnostics, and tachometer display. The PCM supplies 12 volts to the sensor on the 12-volt reference circuit, and provides a ground on the low reference circuit. The CKP sensor provides signals to the PCM on the medium resolution engine speed signal circuit. The PCM monitors the CKP sensor for errors. If the PCM does not receive a signal from the CKP sensor, DTC P0335 sets.

This diagnostic procedure supports the following DTC

DTC P0335 Crankshaft Position (CKP) Sensor Circuit

1. The camshaft position (CMP) sensor signal is incrementing.
2. The mass air flow (MAF) is more than 2 g/s.
3. The engine is cranking or running.
4. The diagnostic runs continuously when the above conditions are met.

The PCM has detected no CKP sensor pulses for more than 2 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The numbers below refer to the step numbers on the diagnostic table.

1. 6: An internally shorted CMP sensor, CKP sensor or a short to ground on either 12-volt reference circuit will set DTCs P0335 and P0340.

1. 8: This step tests for high resistance in the 12-volt reference circuit and the low reference circuit.

1. 10: Any change in RPM verifies that the controller is able to receive a signal.

DTC P0335

The crankshaft position (CKP) sensor is a 24X sensor. The CKP sensor provides 24 digital ON/OFF signals to the powertrain control module (PCM) per revolution of the crankshaft. This information is used by the PCM for ignition timing, fuel injector timing, misfire diagnostics, and tachometer display. The PCM supplies 12 volts to the sensor on the 12-volt reference circuit and provides a ground on the low reference circuit. The CKP sensor provides signals to the PCM on the medium resolution engine speed signal circuit. The PCM monitors the CKP sensor for errors. If the PCM receives an inconsistent signal form the CKP sensor, DTC P0336 sets.

This diagnostic procedure supports the following DTC

DTC P0336 Crankshaft Position (CKP) Sensor Performance

1. The engine is cranking or running.
2. This diagnostic runs continuously once the above conditions are met.

1. The PCM detects that more or less than 48 CKP sensor pulses have occurred for every one camshaft position (CMP) sensor pulse.
2. This conditions exists for more than 2 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

DTC P0336

The camshaft position (CMP) sensor is a 1X sensor. The CMP sensor provides one digital ON/OFF signal to the powertrain control module (PCM) per revolution of the camshaft. This information is used by the PCM to determine the position of the valve train relative to the crankshaft position (CKP). By monitoring the CMP and CKP signals, the PCM can accurately time the operation of the fuel injectors. The PCM supplies 12 volts to the sensor on the 12-volt reference circuit and provides a ground on the low reference circuit. The CMP sensor provides signals to the PCM on the CMP sensor signal circuit. The PCM monitors the CMP sensor for errors. If the PCM does not receive a signal from the CMP sensor, DTC P0340 sets.

This diagnostic procedure supports the following DTC

DTC P0340 Camshaft Position (CMP) Sensor Circuit

1. The engine is cranking or running.
2. This diagnostic runs continuously once the above condition is met.

The PCM detects that the engine has been cranking for more than 10 seconds without a CMP sensor signal.

OR

The PCM detects that when the engine is running, more than 6 CKP sensor low resolution reference signals, generated by the PCM, have occurred for every one CMP sensor signal.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following conditions may cause this DTC to set

1. Incorrect harness routing near secondary ignition components
2. Ignition coil arcing to wiring harness or ignition control (IC) module-Inspect the ignition coils for cracks, carbon tracking, or other signs of damage.
3. Camshaft reluctor wheel damage
4. The sensor coming in contact with the reluctor wheel
5. Foreign material passing between the sensor and the reluctor wheel
6. Excessive camshaft end-play

If the condition is intermittent, refer to Testing for Intermittent Conditions and Poor Connections .

DTC P0340

The camshaft position (CMP) sensor is a 1X sensor. It provides one digital ON/OFF signal to the powertrain control module (PCM) per revolution of the camshaft. This information is used by the PCM to determine the position of the valve train relative to the crankshaft position (CKP). By monitoring the CMP and the CKP signals, the PCM can accurately time the operation of the fuel injectors. The PCM supplies 12 volts to the sensor on the 12-volt reference circuit and provides a ground on the low reference circuit. The CMP sensor provides signals to the PCM on the CMP sensor signal circuit. The PCM monitors the CMP sensor for errors. If the PCM receives an incorrect signal from the CMP sensor, DTC P0341 sets.

This diagnostic procedure supports the following DTC

DTC P0341 Camshaft Position (CMP) Sensor Performance

1. The engine is cranking or running.
2. DTC P0341 runs continuously when the above condition is met.

The PCM detects that less than 6 CKP sensor low resolution reference signals, generated by the PCM, have occurred for every CMP sensor signal.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following conditions may cause this DTC to set

1. Camshaft reluctor ring damage
2. The sensor coming in contact with the reluctor ring
3. Foreign material passing between the sensor and the reluctor ring
4. Wear or damage to the timing chain or sprockets-Refer to «Timing Chain and Sprockets Cleaning and Inspection»(ref-239708-S11716963042006080100000) .
5. Excessive camshaft end-play
6. Wiring routed too close to secondary ignition components

If you suspect the condition is intermittent, refer to Testing for Intermittent Conditions and Poor Connections .

The numbers below refer to the step numbers on the diagnostic table.

1. 3: This step inspects for electromagnetic interference (EMI) on the CMP sensor circuits.
2. 6: Damage to the face of the sensor could indicate foreign material passing between the CMP sensor and the reluctor wheel. This condition would cause this DTC to set. Damage to the reluctor wheel would affect the CMP sensor output.

DTC P0341

There are three dual-tower ignition coils integrated with the ignition control module (ICM). The ICM contains coil driver circuits that operate the 3 coils. The ICM wiring includes the following circuits

1. An ignition 1 voltage circuit
2. A ground circuit
3. An ignition coil (IC) 1 control circuit
4. An IC 2 control circuit
5. An IC 3 control circuit
6. A low reference circuit

The powertrain control module (PCM) controls each ignition coil by transmitting timing pulses to the ICM on each of the IC control circuits to enable properly timed spark events. The IC 1 controls spark for cylinders 1 and 4. The IC 2 controls spark for cylinders 2 and 5. The IC 3 controls spark for cylinders 3 and 6.

If the PCM detects an incorrect voltage on any of the IC control circuits, the corresponding DTC sets.

This diagnostic procedure supports the following DTCs

1. DTC P0351 Ignition Coil 1 Control Circuit
2. DTC P0352 Ignition Coil 2 Control Circuit
3. DTC P0353 Ignition Coil 3 Control Circuit

1. The engine is cranking or running.
2. The DTCs run continuously when the above conditions are met.

The PCM detects an incorrect voltage in an IC control circuit for 90 out of 100 engine cycles.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

DTC P0351, P0352, or P0353

The control module tests the exhaust gas recirculation (EGR) system during deceleration. The control module does this by momentarily commanding the EGR valve to open while monitoring the signal circuit of the manifold absolute pressure (MAP) sensor. When the EGR valve is opened, the control module will expect to see a predetermined increase in MAP. If the expected increase in MAP is not detected, the control module records the amount of MAP difference that was detected and adjusts a calibrated fail counter towards a calibrated fail threshold level. The number of EGR flow test counts required to exceed the fail threshold may vary according to the amount of detected EGR flow error.

The EGR valve position sensor is monitored by the control module. The 5-volt reference circuit, the low reference circuit, and the EGR valve position signal circuit are used by the control module to determine the EGR valve position. The control module compares the EGR Position Sensor parameter with the desired EGR Position parameter when the valve is commanded open or closed.

The control module controls the EGR valve with a solid state device called a driver. The driver supplies the EGR solenoid with 12 volts that is pulse width modulated (PWM) through the EGR solenoid high control circuit. A ground path is provided by the control module through the EGR solenoid low control circuit. The driver has the ability to detect an electrical malfunction on the EGR solenoid control circuits.

When the ignition switch is turned ON, the control module records the EGR Learned Minimum Position. The control module compares the EGR Learned Minimum Position parameter to the EGR Position Sensor parameter.

The control module will only allow one EGR flow test during an ignition cycle. To aid in verifying a repair, the control module will allow between 9 and 16 EGR flow test counts during the first ignition cycle following a code clear event.

1. DTCs P0068, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0300, P0335, P0403, P0404, P0405, P0502, P0503, P0506, P0507, P0604, P0606, P0641, P0651, P1106, P1107, P1125, P2101, P2108, P2135, U0107 are not set.
2. The engine run time may need to be more than 3 minutes.
3. The Ignition 1 Signal parameter is between 11-18 volts.
4. The AC Relay Command parameter does not change.
5. The EGR position is less than 1 percent.
6. The transmission is in third or fourth gear.
7. The Current Gear parameter does not change.
8. The decel fuel cut-off (DFCO) mode is not active.
9. The Intake Air Temperature (IAT) sensor parameter is between 5-100°C (41-212°F).
10. The Engine Coolant Temperature (ECT) sensor parameter is between 75-123°C (167-253°F).
11. The Engine Speed parameter is between 1,000-1,500 RPM.
12. The Manifold Absolute Pressure (MAP) sensor parameter is between 17-43 kPa.
13. The Barometric Pressure (BARO) parameter is more than 74 kPa.
14. The Throttle Position (TP) sensor parameter is less than 1 percent.
15. The Vehicle Speed sensor parameter is between 45-113 km/h (28-70 mph) during deceleration.
16. The vehicle will need to be driven more than 80 km/h (50 mph), and then allowed to decelerate. When the vehicle is decelerating, while meeting all of the criteria listed above, the PCM will enable the EGR flow test to run. As the EGR flow test is running, you will see the desired EGR Position parameter and the EGR Position Sensor parameter on the scan tool momentarily change from 0 to a calibrated value above 0. Additionally, the EGR Flow Test Count parameter on the scan tool will increment when each EGR flow test is completed.

The MAP changes monitored by the PCM during the EGR flow tests indicate an insufficient amount of EGR flow.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Inspect for the following conditions

1. A vacuum restriction to the MAP sensor-A skewed MAP sensor reading can cause the PCM to read incorrect MAP changes during the EGR flow test.
2. An engine that is running poorly due to a mechanical condition such as worn piston rings, worn camshaft, etc.-These types of conditions can cause low engine vacuum and thus can cause a less than expected MAP change during the flow test.
3. Excessive back pressure in the exhaust system may cause this DTC to set. This condition can cause low engine vacuum and thus can cause a less than expected MAP change during the EGR flow test. Possible causes of this could be a restriction in the exhaust system or non original equipment manufacture (OEM) exhaust parts.
4. Exhaust system leaks can cause an insufficient amount of EGR flow through the EGR valve. This condition can cause a less than expected MAP change due to insufficient exhaust back pressure. Possible causes of this could be a leaking exhaust system, a leaking EGR pipe or non OEM exhaust parts.
5. A restriction in the intake manifold such as carbon deposits and casting flash

Engine Controls Schematics

1. «Powertrain Control Module (PCM) Connector End Views»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__powertrain-control-module-pcm-connector-end)
2. «Engine Controls Connector End Views»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__engine-controls-connector-end-views)

1. «Circuit Testing»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__circuit-testing)
2. «Connector Repairs»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__wiring-repairs)

Scan Tool Reference

1. «Scan Tool Data List»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-1-of-2__scan-tool-data-list)
2. «Scan Tool Data Definitions»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-1-of-2__scan-tool-data-definitions)

Circuit/System Verification

Operate the vehicle within the Conditions for Running the DTC. Observe the EGR Flow Test Count parameter on the scan tool. EGR Flow Test counts may need to be as many as 16 to pass this DTC after the DTCs have been cleared.

1. Test the MAP Sensor for being shifted, stuck, skewed, and for correct vacuum supply. Refer to «Manifold Absolute Pressure (MAP) Sensor Diagnosis»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-troubleshooting-diagnosis) .
2. Inspect for a vacuum leak between the exhaust gas recirculation (EGR) valve and the intake manifold.
3. Inspect the exhaust system for leaks, restrictions, and for modification of original equipment manufacture (OEM) parts.
4. Remove the EGR valve and inspect for the following: cracks heat distress pintle for corrosion EGR Valve Passages for restriction EGR passage in the intake manifold for carbon buildup, casting flash or other restriction If a restriction is identified, refer to «Exhaust Gas Recirculation (EGR) System Cleaning»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__exhaust-gas-recirculation-egr-system-cleaning) . If a condition with the EGR valve is identified, replace the EGR Valve.
5. Inspect the engine for correct valve timing and lift or for other conditions that might affect engine vacuum source.

1. «Control Module References»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__control-module-references) for control module replacement and programming.
2. «Exhaust Gas Recirculation (EGR) Valve Replacement»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2)

The control module tests the exhaust gas recirculation (EGR) system during deceleration. The control module does this by momentarily commanding the EGR valve to open while monitoring the signal circuit of the manifold absolute pressure (MAP) sensor. When the EGR valve is opened, the control module will expect to see a predetermined increase in MAP. If the expected increase in MAP is not detected, the control module records the amount of MAP difference that was detected and adjusts a calibrated fail counter towards a calibrated fail threshold level. The number of EGR flow test counts required to exceed the fail threshold may vary according to the amount of detected EGR flow error.

The EGR valve position sensor is monitored by the control module. The 5-volt reference circuit, the low reference circuit, and the EGR valve position signal circuit are used by the control module to determine the EGR valve position. The control module compares the EGR Position Sensor parameter with the desired EGR Position parameter when the valve is commanded open or closed.

The control module controls the EGR valve with a solid state device called a driver. The driver supplies the EGR solenoid with 12 volts that is pulse width modulated (PWM) through the EGR solenoid high control circuit. A ground path is provided by the control module through the EGR solenoid low control circuit.

When the ignition switch is turned ON, the control module records the EGR Learned Minimum Position. The control module compares the EGR Learned Minimum Position parameter to the EGR Position Sensor parameter.

The control module has the ability to detect an electrical malfunction on the EGR solenoid control circuits.

1. The engine is cranking or running.
2. The Ignition 1 Signal parameter is between 11-18 volts.

1. The PCM detects an electrical malfunction in the EGR solenoid high control circuit or the EGR solenoid low control circuit.
2. The above condition is met for more than 20 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Engine Controls Schematics

1. «Powertrain Control Module (PCM) Connector End Views»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__powertrain-control-module-pcm-connector-end)
2. «Engine Controls Connector End Views»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__engine-controls-connector-end-views)

1. «Circuit Testing»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__circuit-testing)
2. «Connector Repairs»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__wiring-repairs)

1. «Scan Tool Data List»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-1-of-2__scan-tool-data-list)
2. «Scan Tool Data Definitions»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-1-of-2__scan-tool-data-definitions)

With the ignition ON and the engine OFF, command the EGR from 0-100 percent. The EGR Position Sensor parameter should remain within 3 percent of the Desired EGR Position parameter.

1. Disconnect the EGR valve harness connector and probe the EGR High Control circuit with a test lamp connected to ground. Command the EGR valve from 0% to 10% and back to 0%. The test lamp should illuminate when commanded to 10%. If the test lamp remains illuminated when commanded to 0%, test the EGR High Control circuit for a short to voltage. If the test lamp does not illuminate, test the EGR High Control circuit for an open, high resistance, or short to ground.
2. Connect a test lamp between the EGR High Control circuit and the EGR Low Control Circuit. Command the EGR valve from 0% to 10% and back to 0%. The test lamp should illuminate when commanded to 10%. If the test lamp illuminates when commanded to 10% replace the EGR Valve. If the test lamp does not illuminate, test the EGR Low Control circuit for an open, high resistance. If all circuits test OK, replace the control module.

1. «Control Module References»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__control-module-references) for control module replacement and programming.
2. «Exhaust Gas Recirculation (EGR) Valve Replacement»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2)

The control module tests the exhaust gas recirculation (EGR) system during deceleration. The control module does this by momentarily commanding the EGR valve to open while monitoring the signal circuit of the manifold absolute pressure (MAP) sensor. When the EGR valve is opened, the control module will expect to see a predetermined increase in MAP. If the expected increase in MAP is not detected, the control module records the amount of MAP difference that was detected and adjusts a calibrated fail counter towards a calibrated fail threshold level. The number of EGR flow test counts required to exceed the fail threshold may vary according to the amount of detected EGR flow error.

The EGR valve position sensor is monitored by the control module. The 5-volt reference circuit, the low reference circuit, and the EGR valve position signal circuit are used by the control module to determine the EGR valve position. The control module compares the EGR Position Sensor parameter with the desired EGR Position parameter when the valve is commanded open or closed.

The control module controls the EGR valve with a solid state device called a driver. The driver supplies the EGR solenoid with 12 volts that is pulse width modulated (PWM) through the EGR solenoid high control circuit. A ground path is provided by the control module through the EGR solenoid low control circuit. The driver has the ability to detect an electrical malfunction on the EGR solenoid control circuits.

When the ignition switch is turned ON, the control module records the EGR Learned Minimum Position. The control module compares the EGR Learned Minimum Position parameter to the EGR Position Sensor parameter.

The control module is able to determine the difference between the actual EGR position and the desired EGR position when the EGR is commanded open.

1. The Ignition 1 Signal parameter is more than 11 volts.
2. The EGR command will be disabled if the start-up engine coolant temperature (ECT) is less than 5°C (41°F) and will not enable until the ECT is more than 75°C (167°F).
3. The EGR valve is commanded to open.
4. The EGR flow test is not running.

1. The difference between the EGR Position Sensor parameter and the desired EGR Position parameter is more than 15 percent.
2. The above condition is met for more than 20 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Engine Controls Schematics

1. «Powertrain Control Module (PCM) Connector End Views»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__powertrain-control-module-pcm-connector-end)
2. «Engine Controls Connector End Views»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__engine-controls-connector-end-views)

1. «Circuit Testing»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__circuit-testing)
2. «Connector Repairs»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__wiring-repairs)

1. «Scan Tool Data List»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-1-of-2__scan-tool-data-list)
2. «Scan Tool Data Definitions»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-1-of-2__scan-tool-data-definitions)

With the ignition ON and the engine OFF, command the EGR from 0-100 percent. The EGR Position Sensor parameter should remain within 3 percent of the Desired EGR Position parameter.

1. With the ignition ON and the engine OFF, observe the DTC information on the scan tool. If DTC P0641 is also set, diagnose this DTC first. Refer to DTC P0641 in «Diagnostic Trouble Code (DTC) List - Vehicle»(/chevrolet/equinox/i-2004-2009/remont/oem-general-information/#vehicle-dtc-information__diagnostic-trouble-code-dtc-list) .
2. Disconnect the EGR harness connector and observe the EGR Position Sensor parameter. The EGR Position Sensor parameter should display 0%. If the EGR Position Sensor parameter is more than 0% test the EGR Position Sensor signal circuit for a short to voltage or a faulty control module.
3. Using a 3 amp fused jumper wire jumper the EGR 5 volt reference circuit to the EGR Position Sensor Signal circuit at the EGR harness connector and monitor the EGR Position Sensor parameter. The EGR Position Sensor parameter should display 99%. If the EGR Position Sensor parameter is less than 99% test for an open, high resistance, or a short to ground in the EGR Pintle Position Signal circuit.
4. Disconnect the control module and measure the resistance of the EGR High Control circuit and the EGR Low Control circuit. There should be less than 3ohm of resistance on each circuit. If the resistance is more than 3ohm, test each circuit for high resistance.

1. If all circuits test OK, replace the EGR Valve.

1. «Control Module References»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__control-module-references) for control module replacement and programming.
2. «Exhaust Gas Recirculation (EGR) Valve Replacement»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2)

The control module tests the exhaust gas recirculation (EGR) system during deceleration. The control module does this by momentarily commanding the EGR valve to open while monitoring the signal circuit of the manifold absolute pressure (MAP) sensor. When the EGR valve is opened, the control module will expect to see a predetermined increase in MAP. If the expected increase in MAP is not detected, the control module records the amount of MAP difference that was detected and adjusts a calibrated fail counter towards a calibrated fail threshold level. The number of EGR flow test counts required to exceed the fail threshold may vary according to the amount of detected EGR flow error.

The EGR valve position sensor is monitored by the control module. The 5-volt reference circuit, the low reference circuit, and the EGR valve position signal circuit are used by the control module to determine the EGR valve position. The control module compares the EGR Position Sensor parameter with the desired EGR Position parameter when the valve is commanded open or closed.

The control module controls the EGR valve with a solid state device called a driver. The driver supplies the EGR solenoid with 12 volts that is pulse width modulated (PWM) through the EGR solenoid high control circuit. A ground path is provided by the control module through the EGR solenoid low control circuit. The driver has the ability to detect an electrical malfunction on the EGR solenoid control circuits.

When the ignition switch is turned ON, the control module records the EGR Learned Minimum Position. The control module compares the EGR Learned Minimum Position parameter to the EGR Position Sensor parameter.

The control module is able to determine if the EGR valve position sensor signal voltage is too low.

1. The EGR command will be disabled if the start-up ECT is less than 5°C (41°F) and will not enable until the ECT is more than 75°C (167°F).
2. The EGR flow test is not running.
3. The Ignition 1 Signal parameter is more than 11 volts.

1. The EGR Position Sensor parameter is less than 0.35 volts.
2. The above condition is met for more than 20 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Engine Controls Schematics

1. «Powertrain Control Module (PCM) Connector End Views»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__powertrain-control-module-pcm-connector-end)
2. «Engine Controls Connector End Views»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__engine-controls-connector-end-views)

1. «Circuit Testing»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__circuit-testing)
2. «Connector Repairs»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__wiring-repairs)

1. «Scan Tool Data List»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-1-of-2__scan-tool-data-list)
2. «Scan Tool Data Definitions»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-1-of-2__scan-tool-data-definitions)

With the ignition ON and the engine OFF, command the EGR from 0-100 percent. The EGR Position Sensor parameter should remain within 3 percent of the Desired EGR Position parameter.

1. With the ignition ON and the engine OFF, observe the DTC information on the scan tool. If DTC P0641 is also set, diagnose this DTC first. Refer to DTC P0641 in «Diagnostic Trouble Code (DTC) List - Vehicle»(/chevrolet/equinox/i-2004-2009/remont/oem-general-information/#vehicle-dtc-information__diagnostic-trouble-code-dtc-list) .
2. Disconnect the EGR harness connector and measure the EGR 5 volt Reference circuit for 4.8-5.2 volts. If the voltage is less than 4.8 volts test the EGR Valve 5 Volt Reference circuit for an open, high resistance, a short to ground, or a short to the EGR Low Control circuit. If the voltage is more than 5.2 volts test the EGR Valve 5 Volt Reference circuit for a short to voltage or a short to the EGR High Control circuit.
3. Using a 3 amp fused jumper wire connect the EGR Valve 5 Volt Reference circuit to the EGR Position Signal circuit and observe the EGR Position Sensor parameter for more than 4.9 volts. If the EGR Position Sensor parameter is less than 4.9 volts test the EGR Position Signal circuit for an open or high resistance or a short to ground.
4. Using a 3 amp fused jumper wire connect the EGR High Control circuit to the EGR Low Control circuit at the EGR harness connector. Command the EGR Valve to 10% while monitoring the EGR Position Sensor parameter. The EGR Position Sensor parameter should remain at 0%. If the EGR Position Sensor parameter is more than 0% test the EGR Position Signal circuit for a short to the EGR High Control circuit. If all circuits test OK, replace the EGR Valve.

1. «Control Module References»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__control-module-references) for control module replacement and programming.
2. «Exhaust Gas Recirculation (EGR) Valve Replacement»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2)

The control module tests the exhaust gas recirculation (EGR) system during deceleration. The control module does this by momentarily commanding the EGR valve to open while monitoring the signal circuit of the manifold absolute pressure (MAP) sensor. When the EGR valve is opened, the control module will expect to see a predetermined increase in MAP. If the expected increase in MAP is not detected, the control module records the amount of MAP difference that was detected and adjusts a calibrated fail counter towards a calibrated fail threshold level. The number of EGR flow test counts required to exceed the fail threshold may vary according to the amount of detected EGR flow error.

The EGR valve position sensor is monitored by the control module. The 5-volt reference circuit, the low reference circuit, and the EGR valve position signal circuit are used by the control module to determine the EGR valve position. The control module compares the EGR Position Sensor parameter with the desired EGR Position parameter when the valve is commanded open or closed.

The control module controls the EGR valve with a solid state device called a driver. The driver supplies the EGR solenoid with 12 volts that is pulse width modulated (PWM) through the EGR solenoid high control circuit. A ground path is provided by the control module through the EGR solenoid low control circuit. The driver has the ability to detect an electrical malfunction on the EGR solenoid control circuits.

When the ignition switch is turned ON, the control module records the EGR Learned Minimum Position. The control module compares the EGR Learned Minimum Position parameter to the EGR Position Sensor parameter.

The control module is able to determine if the EGR valve position sensor signal voltage is too high.

1. DTC P0641 and P0651 are not set.
2. The Ignition 1 Signal parameter is more than 11 volts.
3. The engine is running.
4. The DTC P0401 intrusive test is not active.
5. The EGR valve is not being commanded with a scan tool.
6. The EGR command will be disabled if the start-up ECT is less than 5°C (41°F) and will not enable until the ECT Sensor parameter is more than 75°C (167°F).
7. DTC P0406 runs continuously when the above conditions are met.

The EGR Position Sensor parameter is more than 94.7 percent of the 5-volt reference voltage for longer than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Engine Controls Schematics

1. «Powertrain Control Module (PCM) Connector End Views»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__powertrain-control-module-pcm-connector-end)
2. «Engine Controls Connector End Views»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__engine-controls-connector-end-views)

1. «Circuit Testing»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__circuit-testing)
2. «Connector Repairs»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__wiring-repairs)

1. «Scan Tool Data List»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-1-of-2__scan-tool-data-list)
2. «Scan Tool Data Definitions»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-1-of-2__scan-tool-data-definitions)

With the ignition ON and the engine OFF, command the EGR from 0-100 percent. The EGR Position Sensor parameter should remain within 3 percent of the Desired EGR Position parameter.

With the ignition ON and the engine OFF, command the EGR from 0-100 percent. The EGR Position Sensor parameter should remain within 3 percent of the Desired EGR Position parameter.

1. With the ignition ON and the engine OFF, observe the DTC information on the scan tool. If DTC P0641 is also set, diagnose this DTC first. Refer to DTC P0641 in «Diagnostic Trouble Code (DTC) List - Vehicle»(/chevrolet/equinox/i-2004-2009/remont/oem-general-information/#vehicle-dtc-information__diagnostic-trouble-code-dtc-list) .
2. Disconnect the EGR harness connector and measure the EGR 5 volt Reference circuit for 4.8-5.2 volts. If the voltage is less than 4.8 volts test the EGR Valve 5 Volt Reference circuit for an open, high resistance, a short to ground, or a short to the EGR Low Control circuit. If the voltage is more than 5.2 volts test the EGR Valve 5 Volt Reference circuit for a short to voltage or a short to the EGR High Control circuit.
3. Using a 3 amp fused jumper wire connect the EGR 5 Volt Reference circuit to the EGR Position Signal circuit, and observe the EGR Position Sensor parameter for more than 4.9 volts If the EGR Position Sensor parameter is less than 4.9 volts test the EGR Position Signal circuit for an open or high resistance or a short to ground.
4. Using a 3 amp fused jumper wire connect the EGR High Control circuit to the EGR Low Control circuit at the EGR harness connector. Command the EGR Valve to 10% while monitoring the EGR Position Sensor parameter. The EGR Position Sensor parameter should remain at 0%. If the EGR Position Sensor parameter is more than 0% test the EGR Position Signal circuit for a short to the EGR High Control circuit. If all circuits test OK, replace the EGR Valve.

1. «Control Module References»(/chevrolet/equinox/i-2004-2009/remont/communication-devices/#computerintegrating-systems__control-module-references) for control module replacement and programming.
2. «Exhaust Gas Recirculation (EGR) Valve Replacement»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2)

A three-way catalytic (TWC) converter controls emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx). The catalyst within the converter promotes a chemical reaction which oxidizes the HC and the CO that are present in the exhaust gas. This process converts the HC and the CO into water vapor and carbon dioxide (CO2), and reduces the NOx, converting the NOx into nitrogen. The catalytic converter also stores oxygen. The powertrain control module (PCM) monitors this process by using a heated oxygen sensor (HO2S) that is in the exhaust stream after the TWC. This HO2S 2, also referred to as the catalyst monitor sensor, produces an output signal that the PCM uses to calculate the oxygen storage capacity of the catalyst. This indicates the ability of the catalyst to convert the exhaust emissions efficiently. The PCM monitors the efficiency of the catalyst by allowing the catalyst to heat, then wait for a stabilization period while the engine is idling. The PCM then adds and removes fuel while monitoring the HO2S 2. When the catalyst is functioning properly, the HO2S 2 response to the extra fuel is slow compared to the response of the HO2S 1, which is located before the TWC. When the HO2S 2 response is near that of the HO2S 1, the oxygen storage capability and efficiency of the catalyst may be degraded below an acceptable threshold. If the PCM detects the degraded condition, DTC P0420 sets.

This diagnostic procedure supports the following DTC.

DTC P0420 Catalyst System Low Efficiency Bank 1

1. DTCs P0030, P0036, P0068, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0125, P0128, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0171, P0172, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0300, P0325, P0327, P0332, P0335, P0336, P0340, P0341, P0401, P0403, P0404, P0405, P0406, P0442, P0443, P0446, P0449, P0455, P0496, P0506, P0507, P1133, P1134, P1258, P1404, P1516, P2101, P2107, P2108, P2119, P2120, P2125, P2135, P2138, P2A00, P2A01, U0107 are not set.
2. The engine has been running for more than 10 minutes.
3. The engine speed is within 200 RPM of the desired idle.
4. The engine coolant temperature (ECT) is between 75-126°C (167-259°F).
5. The barometric pressure (BARO) is more than 74 kPa.
6. The vehicle is in Closed Loop.
7. The intake air temperature (IAT) is between -7 and +100°C (19-212°F).
8. The battery voltage is more than 10.7 volts.
9. The throttle position (TP) is 1.5 percent or less.
10. The short term fuel trim (FT) is between -10 and +10 percent.
11. The engine load must be stable.
12. Warm the catalyst by performing the following procedures: Fully open the hood. Place the transaxle in PARK for automatic transaxle. Place the transaxle is NEUTRAL for manual transaxle, with clutch pedal depressed. Set the parking brake. Press and hold the service brake.
13. This diagnostic attempts 1 test during each valid idle period once the above conditions have been met for 5 seconds. This diagnostic attempts up to 6 tests during each drive cycle. The first test may be run after the initial warm up period of 10 minutes. Maintain engine speed between 2,000-3,000 RPM in park or neutral for 2 minutes. Allow the engine to return to a stabilized idle. Shift into drive for an automatic transmission, without touching the accelerator in order for the test to run. Between each subsequent test, maintain engine speed between 2,000-3,000 RPM in park or neutral for 2 minutes. Allow the engine to return to a stabilized idle. Shift into drive for an automatic transmission, without touching the accelerator in order for the test to run.
14. Test the catalyst by performing the following procedures: Idle the engine and place the vehicle in Drive, or depress the clutch pedal for a manual transmission vehicle, to activate the diagnostic. Within 60 seconds, the air fuel ratio will transition lean, below 14.1, for up to 7 seconds, and then may transition rich, above 15.3, for up to 7 seconds. Verify if DTC P0420 has passed or failed this ignition cycle with the scan tool.

The PCM determines that the efficiency of the catalyst has degraded below a calibrated threshold. This diagnostic may conclude in as few as one test attempt. However, this diagnostic may require as many as 18 test attempts, which would require at least 3 drive cycles. Each test attempt concludes within 2 minutes.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. These conditions may cause a catalytic converter to degrade. Inspect for the following conditions: An engine misfire High engine oil or high coolant consumption Retarded spark timing A weak or poor spark A lean fuel mixture A rich fuel mixture A damaged oxygen sensor or wiring harness The catalyst test may abort if the vehicle falls outside the conditions for running the DTC. The catalyst test may abort due to a change in engine load such as the A/C or engine cooling fan cycling. If 18 tests have been attempted, and the DTC has not run or passed during this key cycle, turn the key to OFF for 30 seconds. Perform the conditions for running a second time.
2. If an intermittent condition cannot be duplicated, the information included in the Freeze Frame/Failure Records can be useful in determining the vehicle operating conditions when the DTC was set.
3. The catalyst may have been temporarily contaminated with a chemical from a fuel additive, fuel contamination, or any of the above conditions.

DTC P0420

The DTC P0442 Evaporative Emission System Leak Detected diagnostic monitors the EVAP system for a small leak. The diagnostic runs when the ignition is in the OFF position and the correct conditions are met. While the vehicle is operating there are sources of heat transferred into the tank from the following

1. Exhaust heat
2. Engine heat
3. Ambient temperature

When the engine is topped and the ignition is in the OFF position a change in the fuel tank vapor temperature occurs. This results in a change in the pressure of the fuel tank vapor space. This change in pressure is monitored by the control module using the fuel tank pressure (FTP) sensor input. The EVAP diagnostic detects leaks as small as 0.51 mm (0.020 in). If the control module detects a change in the fuel tank vacuum/pressure less than a calibrated amount, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected

1. Before the PCM can report DTC P0442 failed, DTCs P0446, P0455 and P0496 must run and pass.
2. DTCs P0112, P0113, P0116, P0117, P0118, P0125, P0128, P0443, P0449, P0451, P0452, P0453, P0462, P0463, P0503, P1106, P1107, P1111, P1112, P1114, P1115, P2610 are not set.
3. The ignition voltage is between 10-18 volts.
4. The barometric pressure (BARO) is more than 75 kPa.
5. The fuel level is between 15-85 percent.
6. The engine coolant temperature (ECT) is between 4-30°C (39-86°F).
7. The intake air temperature (IAT) is between 4-30°C (39-86°F).
8. The start-up ECT and IAT are within 9°C (16°F) of each other.
9. The vehicle speed sensor (VSS) is less than 129 km/h (80 mph).
10. The vehicle must be driven more than 8.4 kilometers (5.2 miles).
11. DTC P0442 runs once per cold start when the above conditions are met.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. To help locate intermittent leaks, use the J 41413-200 Evaporative Emissions System Tester (EEST) to introduce smoke into the EVAP system. See «Special Tools»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__special-tools) . Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light. See «Special Tools»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__special-tools) .
2. To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT . See «Special Tools»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__special-tools) .

The numbers below refer to the step numbers on the diagnostic table.

1. 3: Introducing smoke in 15 second intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
2. 5: This step verifies that repairs are complete.

DTC P0442

An ignition voltage is supplied directly to the evaporative emission (EVAP) canister purge solenoid valve. The EVAP canister purge solenoid valve is pulse width modulated (PWM). The scan tool displays the amount of ON time as a percentage. The control module monitors the status of the driver. The control module controls the EVAP canister purge solenoid valve ON time by grounding the control circuit via an internal switch called a driver. If the control module detects an incorrect voltage for the commanded state of the driver, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0443 Evaporative Emission (EVAP) Purge Solenoid Control Circuit

1. The ignition is in the Crank or Run position.
2. The system voltage is between 11-18 volts.
3. DTC P0443 runs continuously once the above conditions are met.

1. The control module detects that the commanded state of the driver and the actual state of the control circuit Do NOT match.
2. The above condition is present for a minimum of 2 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

DTC P0443

This DTC tests the evaporative emission (EVAP) system for a restricted or blocked EVAP vent path. The control module commands the EVAP canister purge solenoid valve Open and the EVAP canister vent solenoid valve Closed. This allows vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the EVAP canister purge solenoid valve Closed and the EVAP canister vent solenoid valve Open. The control module monitors the fuel tank pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 inches H2O in a calibrated time, this DTC sets.

The following table illustrates the relationship between the ON and OFF states, and the Open or Closed states of the EVAP canister purge and vent solenoid valves.

DTC P0446

This diagnostic procedure supports the following DTC

DTC P0446 Evaporative Emission (EVAP) Vent System Performance

1. Before the PCM can report DTC P0446 failed, DTCs P0442 and P0496 must run and pass.
2. DTCs P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0125, P0128, P0443, P0449, P0451, P0452, P0453, P0455, P0502, P1106, P1107, P1111, P1112, P1114, P1115, P1125, P1516, P2101, P2108, P2119, P2120, P2125, P2138 are not set.
3. The ignition voltage is between 10-18 volts.
4. The barometric pressure (BARO) is more than 75 kPa.
5. The fuel level is between 15-85 percent.
6. The engine coolant temperature (ECT) is between 4-30°C (39-86°F).
7. The intake air temperature (IAT) is between 4-30°C (39-86°F).
8. The start-up ECT and IAT are within 9°C (16°F) of each other.
9. The vehicle speed sensor (VSS) is less than 129 km/h (80 mph).
10. DTC P0446 runs once per cold start when the above conditions are met.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. When using the Evaporative Emission System Tester (EEST) to apply pressure, you can regulate the amount of pressure by activating the remote switch on and off while observing pressure in the EVAP system using a scan tool. DO NOT use more than 5 inches H2O. More than 5 inches H2O applied to the EVAP system can cause the canister vent solenoid valve to temporarily remain in the closed position, which could lead to misdiagnosis in this procedure.
2. An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP canister vent solenoid valve inlet, or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill problem.
3. For intermittent conditions, refer to «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor) .

The number below refers to the step number on the diagnostic table.

1. 3: This test determines if the failure is present or intermittent.

DTC P0446

An ignition voltage is supplied to the evaporative emission (EVAP) canister vent solenoid valve. The control module grounds the EVAP canister vent solenoid valve control circuit to close the solenoid by means of an internal switch called a driver. The scan tool displays the commanded state of the EVAP canister vent solenoid valve as ON or OFF. The control module monitors the status of the driver. If the control module detects an incorrect voltage for the commanded state of the driver, this DTC sets.

The following table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP canister vent solenoid valve.

DTC P0449

This diagnostic procedure supports the following DTC

DTC P0449 Evaporative Emission (EVAP) Vent Solenoid Control Circuit

1. The ignition is in the Crank or Run position.
2. The system voltage is between 11-18 volts.
3. DTC P0449 runs continuously once the above conditions are met.

1. The control module detects that the commanded state of the driver and the actual state of the control circuit do NOT match.
2. The above condition is present for a minimum of 2 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

DTC P0449

The fuel tank pressure (FTP) sensor measures air pressure or vacuum in the evaporative emission (EVAP) system. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal voltage varies depending on EVAP system pressure or vacuum. The controller uses this FTP signal to determine atmospheric pressure for use in the engine-off small leak test, DTC P0442. Before using this signal as an atmospheric reference it must first be re-zeroed. If the FTP signal is out of range during the re-zero procedure, this DTC will set.

This diagnostic procedure supports the following DTC

DTC P0451 Fuel Tank Pressure (FTP) Sensor Performance

1. DTC P0451 runs only when the engine-off natural vacuum small leak test, DTC P0442, executes.
2. The number of times this test runs can range from 0-2 per engine-off period. The length of the test can be up to 10 minutes.

This DTC will set if the controller is unable to re-zero the FTP sensor voltage within a calibrated range during the engine-off small leak test, P0442.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

1. The control module turns OFF the MIL after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and DTC with a scan tool.

1. A restriction in the EVAP canister or vent lines could prevent fuel vapor pressure from bleeding off fast enough. If the vent system cannot bleed off pressure fast enough, the re-zero procedure may not complete successfully, which could cause this code to set. By using the purge solenoid command on a scan tool, vacuum can be applied to the system instead of pressure. With the EVAP canister vent solenoid valve open and the EVAP canister purge solenoid valve commanded to 100 percent, the vacuum should not increase to more than 9 inches H2O.
2. Ensure that the reference port on the FTP sensor is unobstructed.

DTC P0451

The fuel tank pressure (FTP) sensor measures the difference between the air pressure or vacuum in the evaporative emission (EVAP) system, and the outside air pressure. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal circuit voltage varies depending on EVAP system pressure or vacuum. If the FTP sensor signal voltage goes below a calibrated value, this DTC sets.

The following table illustrates the relationship between the FTP sensor signal voltage and the EVAP system pressure/vacuum.

DTC P0452

This diagnostic procedure supports the following DTC

DTC P0452 Fuel Tank Pressure (FTP) Sensor Circuit low Voltage

1. The key is ON.
2. DTC P0452 runs continuously when the above condition is met.

The FTP sensor voltage is less than 0.1 volt for more than 5 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

DTC P0452

The fuel tank pressure (FTP) sensor measures the difference between the air pressure or vacuum in the evaporative emission (EVAP) system, and the outside air pressure. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal circuit voltage varies depending on EVAP system pressure or vacuum. If the FTP sensor signal voltage increases above a calibrated value, this DTC sets.

The following table illustrates the relationship between FTP sensor signal voltage and the EVAP system pressure/vacuum.

DTC P0453

This diagnostic procedure supports the following DTC

DTC P0453 Fuel Tank Pressure (FTP) Sensor Circuit High Voltage

1. The key is ON.
2. DTC P0453 runs continuously when the above conditions are met.

The FTP sensor voltage is more than 4.9 volts for more than 5 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The number below refers to the step number on the diagnostic table.

1. 2: If DTC P0651 set, the 5-volt reference circuit may be shorted to a voltage.

DTC P0453

The fuel tank pressure (FTP) sensor measures air pressure or vacuum in the evaporative emission (EVAP) system. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal voltage varies depending on EVAP system pressure or vacuum. This DTC will set if the control module detects an intermittent signal from the FTP that would prevent the engine-off small leak test, DTC P0442, from running.

This diagnostic procedure supports the following DTC

DTC P0454 Fuel Tank Pressure (FTP) Sensor Circuit Intermittent

1. DTC P0454 runs only when the engine-off natural vacuum small leak test, DTC P0442, executes.
2. This test can run once per engine-off period. The length of the test can be up to 45 minutes.

If, during the engine-off natural vacuum small leak test, DTC P0442, the engine control module (ECM) detects an abrupt FTP signal change, other than a refueling event, this DTC will set. An abrupt change is defined as a change of 1 inch H2O in the span of 1 second.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

1. The control module turns OFF the MIL after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and DTC with a scan tool.

1. This diagnostic is designed to detect an unexpected abrupt voltage signal change from the FTP. Unusual fuel-filling practices, such as repeatedly adding small amounts of fuel, less than 10 percent of tank capacity, could set this DTC. Normal fuel filling procedures will not set this DTC.
2. Scan tool output controls, snapshot, and plot functions can help detect erratic sensor response. To look at the sensor signal under vacuum conditions, use snapshot and the purge/seal function to capture data while commanding purge to 30 percent, and then plot the data to look for erratic sensor operation. A similar inspection can be done for the pressure side of the sensor range by applying pressure with the J 41413-200 Evaporative Emissions System Tester (EEST) while taking a snapshot. See «Special Tools»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__special-tools) .
3. Ensure that the reference port on the FTP sensor is unobstructed.

DTC P0454

The control module tests the evaporative emission (EVAP) system for a large leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the EVAP system vacuum level. When the conditions for running are met, the control module commands the EVAP canister purge solenoid valve OPEN and the EVAP canister vent solenoid valve CLOSED. This allows engine vacuum to enter the EVAP system. At a calibrated time, or vacuum level, the control module commands the EVAP canister purge solenoid valve closed, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum level. If the system is unable to achieve the calibrated vacuum level, or if the vacuum level decreases too rapidly, this DTC sets.

The following table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP canister purge and vent solenoid valves.

DTC P0455

This diagnostic procedure supports the following DTC

DTC P0455 Evaporative Emission (EVAP) System Large Leak Diagnostic

1. Before the PCM can report DTC P0455 failed, DTC P0496 must run and pass.
2. DTCs P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0125, P0128, P0220, P0443, P0446, P0449, P0452, P0453, P0455, P0502, P1106, P1107, P1111, P1112, P1114, P1115, P1125, P1516, P2101, P2108, P2119, P2120, P2125, P2135, P2138 are not set.
3. The ignition voltage is between 10-18 volts.
4. The barometric pressure (BARO) is more than 75 kPa.
5. The fuel level is between 15-85 percent.
6. The engine coolant temperature (ECT) is between 4-30°C (39-86°F).
7. The intake air temperature (IAT) is between 4-30°C (39-86°F).
8. The start-up ECT and IAT are within 9°C (16°F) of each other.
9. The vehicle speed sensor (VSS) is less than 129 km/h (80 mph).
10. DTC P0455 runs once per cold start when the above conditions are met.

The EVAP system is not able to achieve or maintain vacuum during the diagnostic test.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. To help locate intermittent leaks, use the J 41413-200 Evaporative Emissions System Tester (EEST) to introduce smoke into the EVAP system. See «Special Tools»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__special-tools) . Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light. See «Special Tools»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__special-tools) . Introducing smoke in 15 second intervals will allow less pressure into the EVAP system. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
2. A temporary blockage in the EVAP canister purge solenoid valve, purge pipe, or EVAP canister could cause an intermittent condition. Inspect and repair any restriction in the EVAP system.
3. To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT . See «Special Tools»(/chevrolet/equinox/i-2004-2009/remont/testing-diagnostics/#engine-controls-34l-introduction-2-of-2__special-tools) .
4. Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
5. For intermittent conditions, refer to «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/equinox/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor) .

The number below refers to the step number on the diagnostic table.

1. 6: A normal operating FTP sensor should increase above 5 inches of H2O and stop between 6 inches of H2O and 7 inches of H2O.

DTC P0455

See also:
• Engine Controls Schematics
• Powertrain Control Module (PCM) Connector End Views
• Engine Controls Connector End Views
• Diagnostic System Check - Vehicle
• Testing for Intermittent Conditions and Poor Connections
• Diagnostic Trouble Code (DTC) List - Vehicle
• Electrical Center Identification Views
• Circuit Testing
• Wiring Repairs
• Connector Repairs
• Control Module References
• Symptoms - Hydraulic Brakes
• Exhaust Gas Recirculation (EGR) System Cleaning
• Restricted Exhaust
• Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool)
• Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool)
• Special Tools
• Spark Plug Wire Inspection
• Ignition System Specifications
• CKP System Variation Learn Procedure
• Diagnostic Repair Verification
• Lifting and Jacking the Vehicle
• Testing for Electrical Intermittents
• Probing Electrical Connectors
• Using Connector Test Adapters
• Scan Tool Data List
• Scan Tool Data Definitions
• Road Test Caution
• Three-Way Catalytic Converter Damage Notice
• Exhaust Leakage
• Testing for a Short to Voltage
• Testing for Continuity
• DTC P0335