Engine Controls - 1.6l (l91) - DTC p0201 to DTC p0455 Chevrolet Aveo I

Circuit Description

The engine control module (ECM) enables the appropriate fuel injector pulse for each cylinder. Ignition voltage is supplied to the fuel injectors. The ECM controls each fuel injector by grounding the control circuit via a solid state device called a driver. The ECM monitors the status of each driver. If the control module detects an incorrect voltage for the commanded state of the driver, a diagnostic trouble code (DTC) will set.

DTC Descriptor

This diagnostic procedure supports the following DTCs

1. DTC P0201 Injector 1 Control Circuit
2. DTC P0202 Injector 2 Control Circuit
3. DTC P0203 Injector 3 Control Circuit
4. DTC P0204 Injector 4 Control Circuit

Conditions for Running the DTC

1. The engine speed is more than 700 RPM.
2. The ignition 1 voltage is more than 9 Volts.
3. This DTC runs continuously once the above conditions are met.

Conditions for Setting the DTC

1. The control module detects an incorrect voltage on the fuel injector control circuit.
2. The above condition is met for 5 seconds.

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/Failure Records.

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.

Diagnostic Aids

1. Performing the Fuel Injector Coil Test may help isolate an intermittent condition. Refer to «Fuel Injector Coil Test»(/chevrolet/aveo/i-2003-2008/remont/testing-diagnostics/#engine-controls-16l-l91-troubleshooting-diagnosis) .
2. For an intermittent condition, refer to «Intermittent Conditions»(/chevrolet/aveo/i-2003-2008/remont/testing-diagnostics/#engine-controls-16l-l91-troubleshooting-diagnosis__intermittent-conditions) .

DTC P0201-P0204

The engine control module (ECM) monitors the temperature of the engine coolant for engine control and as an enabling criteria for some diagnostics. The amount of air flow into an engine is proportional to the amount of heat an engine generates. The ECM monitors the amount of air flow into the engine to calculate engine coolant temperature (ECT). The ECM uses the calculated temperature to determine if the engine has warmed up to the thermostat regulating temperature. If the coolant temperature does not increase normally, does not reach the regulating temperature of the thermostat, or goes over the thermostat regulating temperature, diagnostics that use the ECT as enabling criteria may not run when expected. If the engine coolant temperature is stuck in range above a certain threshold, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0217 Engine Coolant Over temperature

1. DTCs P0117, P0118, P0122, P0123, P0502, P0562, P0563, P0606, P2610, and U0101 are not set.
2. The engine has been OFF for more than 6 hours OR The start-up engine coolant temperature (ECT) is less than 45°C (113°F).
3. The engine is running.
4. The ECT is more than 50°C (122°F).
5. The intake air temperature (IAT) is more than 35°C (95°F).
6. The airflow into the engine is less than 35 g/s or the calculated airflow into the engine is less than 33 g/s. If the ECM detects that the airflow into the engine is more than 35 g/s or 33 g/s after the diagnostic runs for 60 seconds, the ECM will not report a pass or fail.
7. This DTC runs once per ignition cycle once the above conditions are met.

The ECM detects that the engine coolant temperature is more than 110°C (230°F) 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.

1. An overheating condition may cause this DTC to set.
2. After starting the engine, the engine coolant temperature should rise steadily, then stabilize after the thermostat opens.
3. Test the ECT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor can result in a driveability condition.
4. Check for the proper operation of the engine cooling system.
5. For an intermittent condition, refer to «Symptoms - Engine Cooling»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system) .

Test Description

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

1. 3: The cooling system could be causing this DTC to set. For example, restricted air flow through the radiator, low coolant level, or the incorrect type of coolant.
2. 6: This step tests for excessive resistance in the ECT circuit.
3. 7: This step isolates the condition. If the temperature changes, test for a condition in the low reference circuit. If the temperature remains the same, test the signal circuit for a condition.

DTC P0217

System Description

The engine control module (ECM) uses information from the crankshaft position (CKP) sensor 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 ECM is able to detect individual misfire events. A misfire rate that is high enough can cause overheating and damage to the 3-way catalytic converter (TWC) under certain driving conditions. The malfunction indicator lamp (MIL) will flash ON and OFF when the conditions for TWC damage are present. If the ECM detects a misfire rate sufficient to cause emission levels to exceed a predetermined value, DTC P0300 sets.

This diagnostic procedure supports the following DTC

DTC P0300 Engine Misfire Detected

1. DTCs P0106, P0107, P0108, P0117, P0118, P0122, P0123, P0315, P0336, P0337, P0341, P0342, and P0502 are not set.
2. The engine speed is between 600-6,500 RPM and steady.
3. The ignition 1 voltage is between 11-16 volts.
4. The engine coolant temperature (ECT) is between -7°C and 120°C (19°F and 248°F).
5. The fuel level is more than 15 percent.
6. The throttle angle is steady within 4 percent.
7. The antilock brake system (ABS) and the traction control system (TCS), if equipped, is not active.
8. The torque management is not active.
9. The transmission is not changing gears.
10. The A/C clutch is not changing states.
11. The ECM is not in fuel shut-off or decel fuel cut-off mode.
12. The ECM is not receiving a rough road signal.
13. DTC P0300 runs continuously when the above conditions are met.

The ECM detects a crankshaft rotation speed variation indicating a misfire sufficient to cause emission levels to exceed a predetermined value.

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.

Excessive vibration from sources other than the engine could cause DTC P0300 to set. The following are possible sources of vibration

1. A tire or wheel that is out of round or out of balance
2. Variable thickness brake rotors
3. A unbalanced or damaged driveline condition
4. Certain rough road conditions
5. Worn or damaged accessory drive component or belt

For an intermittent condition, refer to Intermittent Conditions .

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

1. 2: This step determines if there is a current misfire condition. The scan tool will display increasing counts in the Total Misfire Current Counter parameter if a misfire is occurring.

1. 3: If the Total Misfire Current Counter parameter is incrementing, but the engine is NOT misfiring, this could be caused by an excessive vibration from other sources than the engine.

1. 4: If the actual CKP variation values are not within the learned values, the Total Misfire Current Counter parameter 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 sensor. The calculated error allows the engine control module (ECM) to accurately compensate for reference period variations. This enhances the ability of the ECM to detect misfire events over a wider range of engine speed and load.

The ECM stores the CKP system variation values after a learn procedure has been performed. If the actual CKP variation is not within the CKP system variation compensating valves stored in the ECM, DTC P0300 may set. If the CKP system variation values are not stored in the ECM memory, DTC P0315 sets.

This diagnostic procedure supports the following DTC

DTC P0315 Crankshaft Position (CKP) System Variation Not Learned

1. DTCs P0106, P0107, P0108, P0117, P0118, P0122, P0123, P0132, P0201, P0202, P0203, P0204, P0324, P0327, P0336, P0337, P0341, P0342, P0351, P0352, P0402, P0404, P0405, P0406, P0488, P0502, and P0700 are not set.
2. The engine coolant temperature (ECT) is more than 65°C (149°F).
3. DTC P0315 runs continuously once the above conditions are met.

1. The CKP system variation values are not stored in the ECM memory.
2. The manufacturer enable counter is set to zero.

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. 2: The Crankshaft Position Variation Learn Procedure may have to be repeated up to 5 times before the procedure is learned.

DTC P0315

The engine control module (ECM) identifies engine misfire by detecting variations in crankshaft speed. Crankshaft speed variations can also occur when a vehicle is operating over a rough road. The ECM receives a rough road signal by a gravity sensing rough road sensor or an electronic brake control module (EBCM), if equipped with the anti-lock brake system (ABS). The ABS can detect if the vehicle is on the rough surface based on wheel acceleration/deceleration data supplied by each wheel speed sensor. This information is sent to the ECM by the EBCM through a serial data line. The rough road sensor is a vertical low G-acceleration sensor. By sensing vertical acceleration caused by rough road conditions, the ECM determines if the changes in crankshaft speed are due to engine misfire or are driveline induced. If the ECM can not receive any of those signals, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0317 Rough Road Signal Not Detected

1. The engine is running.
2. DTC P0317 runs continuously once the above condition is met for more than 10 seconds.

The ECM does not detect a rough road signal for more than 9 seconds.

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.

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

1. 11: This step tests for a poor connection at the ECM or the harness connections for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and a poor terminal-to-wire connection.

DTC P0317

The knock sensor (KS) system enables the engine control module (ECM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The KS produces an AC voltage signal that varies depending on the vibration level during engine operation. The ECM adjusts the spark timing based on the amplitude and the frequency of the KS signal. The ECM learns a minimum KS noise level at idle and uses calibrated values for the rest of the engine speed range. The ECM should monitor a normal KS signal within the noise channel. If the ECM malfunctions in a manner that will not allow proper diagnosis of the KS system, DTC P0324 sets.

DTC Descriptors

This diagnostic procedure supports the following DTC

DTC P0324 Knock Sensor (KS) Module Performance

1. DTCs P0106, P0107, and P0108 are not set.
2. The engine speed is more than 1600 RPM.
3. The engine coolant temperature (ECT) is more than 50°C (122°F).
4. The manifold absolute pressure (MAP) is between 10 kPa and 50 kPa which depends on engine speed.
5. DTC P0324 runs continuously once the above conditions are met.

1. The ECM detects an internal malfunction in the KS circuitry that will not allow for the correct diagnosis of the KS system.
2. The above condition is present for 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.

DTC P0324

The knock sensor (KS) enables the engine control module (ECM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The KS produces an AC voltage signal that varies depending on the vibration level during engine operation. The ECM adjusts the spark timing based on the amplitude and the frequency of the KS signal. The ECM receives the KS signal through a signal circuit. The ECM supples a ground circuit to the KS through a low reference circuit. The ECM also supplies a shielded ground circuit to the KS. The ECM learns a KS noise level at idle and uses calibrated values for the rest of the engine speed range. The ECM should monitor a normal KS signal within the noise channel. The circuits between the KS sensor and the ECM consists of the following circuits

1. A signal
2. A low reference
3. A shielded ground

If the ECM detects the KS signal outside of the noise channel, or the KS signal is not present, DTC P0327 sets.

This diagnostic procedure supports the following DTC

DTC P0327 Knock Sensor (KS) Circuit Low Frequency.

1. DTCs P0106, P0107, P0108, P1106, and P1107 are not set.
2. The engine coolant temperature (ECT) is more than 50°C (122°F).
3. The engine speed is more than 1600 RPM.
4. The manifold absolute pressure (MAP) is between 10 kPa and 50 kPa which depends on engine speed.
5. DTC P0327 runs continuously once the above conditions are met.

The ECM detects an incorrect KS signal for more 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.

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.
4. For an intermittent condition, refer to «Intermittent Conditions»(/chevrolet/aveo/i-2003-2008/remont/testing-diagnostics/#engine-controls-16l-l91-troubleshooting-diagnosis__intermittent-conditions) .

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

1. 2: This step determines if the fault is current.

1. 3: This step determines if the fault is intermittent.

DTC P0327

The crankshaft position (CKP) sensor signal indicates the crankshaft speed and position. The CKP sensor produces an AC voltage of different amplitude and frequency. The frequency depends on the velocity of the crankshaft, and the AC voltage output depends on the crankshaft position and battery voltage. The CKP sensor works in conjunction with a 58X reluctor wheel attached to the crankshaft. The engine control module (ECM) can synchronize the ignition timing, fuel injector timing, and spark knock control based on the CKP and the camshaft position (CMP) sensor inputs. The CKP sensor is also used to detect misfire and tachometer display. The CKP sensor signal circuit and the low reference circuits are connected directly to the ECM. The shielded ground circuit is connected to ground. The circuits between the CKP sensor and the ECM consists of the following circuits

1. A CKP sensor signal
2. A CKP sensor low reference
3. A shielded ground

If the ECM detects an incorrect number of CKP pulses from the CKP sensor, DTC P0336 sets.

This diagnostic procedure supports the following DTC

DTC P0336 Crankshaft Position (CKP) Sensor Performance

1. The engine is running.
2. The number of extra or missing teeth is more than or equal to 2 per revolution.
3. DTC P0336 runs continuously once the above conditions are met.

1. The ECM detects extra or missing CKP pulses.
2. The above condition is detected in 10 of 100 crankshaft rotations.

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 crankshaft position (CKP) sensor signal indicates the crankshaft speed and position. The CKP sensor produces an AC voltage of different amplitude and frequency. The frequency depends on the velocity of the crankshaft, and the AC voltage output depends on the crankshaft position and battery voltage. The CKP sensor works in conjunction with a 58X reluctor wheel attached to the crankshaft. The engine control module (ECM) can synchronize the ignition timing, fuel injector timing, and spark knock control based on the CKP and the camshaft position (CMP) sensor inputs. The CKP sensor is also used to detect misfire and tachometer display. The CKP sensor signal circuit and the low reference circuits are connected directly to the ECM. The shielded ground circuit is connected to ground. The circuits between the CKP sensor and the ECM consists of the following circuits

1. A signal
2. A low reference
3. A shielded ground

If the ECM detects no pulses from the CKP sensor, DTC P0337 sets.

This diagnostic procedure supports the following DTC

DTC P0337 Crankshaft Position (CKP) Sensor Circuit Low Duty Cycle

1. The ECM monitors the CKP sensor while the engine is cranking. The ECM uses the CMP sensor to determine if the engine is cranking. If DTC P0341 or P0342 is set, the ECM then monitors the manifold absolute pressure (MAP) sensor signal to determine if the engine is cranking.
2. The engine is cranking.
3. DTC P0337 runs continuously when the above conditions are met.

The ECM detects no CKP pulses during engine cranking for 8 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.

DTC P0337

The camshaft position (CMP) sensor correlates the crankshaft to camshaft position so that the engine control module (ECM) can determine which cylinder is ready to be fueled by an injector. As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor and sends a signal to the ECM through the signal circuit. The CMP sensor circuits are directly connected to the ECM. The CMP sensor also determines which cylinder is misfiring. The circuits between the CMP sensor and the ECM consists of the following

1. A ground circuit
2. A CMP signal circuit

If the ECM detects that a minimum number of CMP re-syncs has not occurred, the ECM fuels the engine by using the alternating synchronous double fire (ASDF) method and DTC P0341 sets.

This diagnostic procedure supports the following DTC

DTC P0341 Camshaft Position (CMP) Sensor Performance

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

The ECM detects an incorrect number of CMP re-syncs has occurred 40 out of 200 tests.

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 P0341

The camshaft position (CMP) sensor correlates the crankshaft to camshaft position so that the engine control module (ECM) can determine which cylinder is ready to be fueled by the injector. As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor and sends a signal to the ECM through the signal circuit. The CMP sensor circuits are directly connected to the ECM. The CMP sensor also determines which cylinder is misfiring. The circuits between the CMP sensor and the ECM consists of the following

1. A ground circuit
2. A CMP signal circuit

If the ECM detects no pulses from the CMP sensor, DTC P0342 sets.

This diagnostic procedure supports the following DTC

DTC P0342 Camshaft Position (CMP) Sensor Low Voltage

1. The engine is running.
2. DTC P0342 runs continuously when the above condition is met.

The ECM detects no CMP pulses in 32 camshaft rotations.

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 P0342

The engine control module (ECM) provides a ground for the ignition coil (IC) control circuits. When the ECM removes the ground path of the ignition primary coil, the magnetic field produced by the coil collapses. The collapsing magnetic field produces a voltage in the secondary coil which ignites the spark plugs. The sequencing and timing are controlled by the ECM. The ignition 1 voltage is directly supplied to the ignition coil from the ECM. The IC circuits are directly connected to the ECM from the ignition coil. The ignition coil consists of the following circuits

1. The ignition 1 voltage
2. The IC 1 and 4 control
3. The IC 2 and 3 control

If the ECM detects an incorrect signal in the IC circuits, DTCs P0351 or P0352 sets.

This diagnostic procedure supports the following DTCs

1. DTC P0351 Ignition Coil 1 and 4 Control Circuit
2. DTC P0352 Ignition Coil 2 and 3 Control Circuit

1. The ignition is ON or the engine is operating.
2. DTCs P0351 and P0352 run continuously once the above condition is met.

The ECM detects an incorrect signal in the IC circuits for 3 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. 2: This step determines if there is a fault within an ignition coil circuit.
2. 4: This step tests the ignition coil. If the frequency is within the specified range, there is a condition with the ignition control circuit or the ECM.

P0351-P0352 Ignition Coil Control Circuit

The engine control module (ECM) performs a flow test on the exhaust gas recirculation (EGR) system during deceleration. The ECM does this by momentarily commanding the EGR valve to open while monitoring the signal of the manifold absolute pressure (MAP) sensor and the EGR position sensor. If the MAP signal is incorrect for the EGR pintle position, the ECM 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 tests required to exceed the fail threshold may vary according to the amount of detected EGR flow error. If the ECM detects an EGR flow error, DTC P0401 sets.

This diagnostic procedure supports the following DTC

DTC P0401 Exhaust Gas Recirculation (EGR) Flow Insufficient

1. DTCs P0106, P0107, P0108, P0112, P0113, P0115, P0117, P0118, P0122, P0123, P0125, P0128, P0201, P0202, P0203, P0204, P0217, P0351, P0352, P0402, P0404, P0405, P0406, P0441, P0488, P0502, P0506, and P0507 are not set.
2. The EGR flow test is performed once per ignition cycle.
3. DTC P0401 runs multiple times on the first ignition cycle after the DTC is cleared from the ECM memory.
4. The EGR flow test is ran in decel fuel cut-off (DFCO) mode with the following conditions present before deceleration occurs: The A/C compressor clutch does not change state during deceleration. The ambient air temperature is more than 3°C (37°F). The engine speed is between 1,550-2,900 RPM for automatic transmission or 1400-2,900 RPM for manual transmission before deceleration. The manifold absolute pressure (MAP) is between 10.3-37 kPa. The barometric pressure (BARO) is more than 72 kPa. The vehicle speed is more than 18 km/h (11 mph) before deceleration.
5. The EGR flow test is ran when the following conditions are met during DFCO mode: The throttle position is less than 1 percent. The EGR position is less than 1 percent. The MAP does not vary more than 1 kPa.
6. DTC P0401 runs continuously once the above conditions are met.

The vehicle speed needs to be more than 18 km/h (11 mph), and then allowed to decelerate. When the vehicle is decelerating, while meeting all of the criteria listed above, the ECM will enable the EGR flow test. 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. The EGR flow test will be disabled if one of the following conditions occur

1. The vehicle speed drops more than 4 km/h (3 mph).
2. The engine speed increases more than 50 RPM during a decel.
3. The actual EGR position is less than 90 percent of the commanded state.

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

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. 3: MAP sensor faults must be diagnosed first. A skewed MAP sensor reading could cause this DTC to set.
2. 7: An engine mechanical condition may cause the engine to operate poorly, which could cause a low vacuum condition.

DTC P0401

The coil of the exhaust gas recirculation (EGR) valve has 12 volts supplied to it by an ignition voltage circuit. The control circuit of the EGR valve is a pulse width modulated (PWM) ground produced by an internal low side driver of the engine control module (ECM). The ECM monitors the position of the EGR pintle through the EGR position sensor. The EGR position sensor sends a feedback voltage on the signal circuit to the ECM. This voltage varies depending on the position of the EGR valve pintle. The ECM interprets this voltage as the position of the EGR valve pintle. If the ECM determines that EGR valve pintle is open during crank, DTC P0402 sets.

This diagnostic procedure supports the following DTC

DTC P0402 Exhaust Gas Recirculation (EGR) Flow Excessive

1. The engine is cranking.
2. The ignition voltage is between 10-16 volts.
3. DTC P0402 runs continuously once the above conditions are met.

The ECM detects excessive EGR flow due to the EGR valve pintle being open more than 70 percent for 3 seconds during crank.

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 P0402

The engine control module (ECM) monitors the position of the exhaust gas recirculation (EGR) valve through the EGR valve position sensor. The EGR valve position sensor sends a feedback voltage on the signal circuit to the ECM. This voltage varies depending on the position of the EGR valve. The ECM interprets this voltage as the position of the EGR valve. If the ECM detects a difference between the actual EGR position and the commanded EGR position, DTC P0404 sets.

This diagnostic procedure supports the following DTC

DTC P0404 Exhaust Gas Recirculation (EGR) Open Position Performance

1. DTCs P0112, P0113, P0405, P0406, and P0502 are not set.
2. The ignition voltage is between 11.7-16 volts.
3. The ambient air temperature is more than 3°C (37°F).
4. The desired EGR position is more than 0 percent and steady within 3 percent.
5. DTC P0404 runs continuously every 125 milliseconds when the above conditions are met.

1. The ECM detects a difference between the actual EGR position and the commanded EGR position of more than 15 percent for more than 30 seconds.
2. The above condition occurs 3 times with 5 seconds between each 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.

DTC P0404

The engine control module (ECM) monitors the position of the exhaust gas recirculation (EGR) valve through the EGR valve position sensor. The EGR valve position sensor sends a feedback voltage on the signal circuit to the ECM. The EGR position sensor voltage varies depending on the position of the EGR valve. If the voltage on the signal circuit of the EGR valve position sensor is less than a calibrated value, DTC P0405 sets.

This diagnostic procedure supports the following DTC

DTC P0405 Exhaust Gas Recirculation (EGR) Position Sensor Circuit Low Voltage

1. The ignition voltage is between 11.7-16 volts.
2. DTC P0405 runs continuously every 125 milliseconds when the above condition is met.

The ECM detects that the EGR position voltage is less than 0.2 volts for more than 10 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.

DTC P0405

The engine control module (ECM) monitors the position of the exhaust gas recirculation (EGR) valve through the EGR valve position sensor. The EGR valve position sensor sends a feedback voltage on the signal circuit to the ECM. The EGR position sensor voltage varies depending on the position of the EGR valve. If the voltage on the signal circuit of the EGR valve position sensor is pulled higher than a calibrated value, DTC P0406 sets.

This diagnostic procedure supports the following DTC

DTC P0406 Exhaust Gas Recirculation (EGR) Position Sensor Circuit High Voltage

1. The ignition 1 voltage is between 11.7-16 volts.
2. DTC P0406 runs continuously every 125 milliseconds when the above condition is met.

The ECM detects the voltage on the signal circuit of the EGR valve position sensor is more than 4.9 volts for more than 10 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.

DTC P0406

Description

A three-way catalytic (TWC) converter controls exhaust 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 is present in the exhaust gas. This process will convert the HC and the CO into water vapor and carbon dioxide (CO2), and will reduce the NOx, converting the NOx into nitrogen. The catalytic converter also stores oxygen. The engine control module (ECM) monitors this process by using a heated oxygen sensor (HO2S) which is in the exhaust stream past the three-way catalytic converter. The HO2S produces an output signal which indicates the oxygen storage capacity of the catalyst. This in turn indicates the catalysts ability to convert the exhaust emissions effectively. The ECM monitors the catalyst efficiency by first allowing the catalyst to heat, then waiting for a stabilization period while the engine is idling. Then, the ECM adds and removes fuel while monitoring the reaction of the HO2S. When the catalyst is functioning properly, the HO2S 2 response to the extra fuel is slow compared to the HO2S 1. When the HO2S 2 response is close to that of the HO2S 1, the oxygen storage capacity or efficiency of the catalyst may be degraded below an acceptable threshold. If the ECM detects the degraded condition DTC P0420 sets.

This diagnostic procedure supports the following DTC

DTC P0420 Catalyst System Low Efficiency

1. DTCs P0106, P0107, P0108, P0115, P0117, P0118, P0122, P0123, P0125, P0128, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0171, P0172, P0201, P0202, P0203, P0204, P0217, P0300, P0336, P0337, P0341, P0342, P0351, P0352, P0402, P0404, P0405, P0406, P0441, P0443, P0488, P0502, P0506, P0507, P0562, P2195, and P2196 are not set.
2. Before the ECM performs the idle test, the vehicle must be driven under the following conditions: The calculated air flow into the engine is more than 7.8 g/s for more than 16 seconds for a manual transmission. The calculated air flow into the engine is more than 11 g/s for more than 11 seconds for an automatic transmission.
3. The transmission is in neutral or drive at idle.
4. The engine is in closed loop fuel control.
5. The EVAP purge concentration is learned.
6. The engine is operating for more than 9.5 minutes.
7. The calculated airflow into the engine at idle is between 2.25-7.5 g/s for an automatic transmission.
8. The calculated airflow into the engine at idle is between 2.25-6.5 g/s for a manual transmission.
9. The throttle position (TP) is less than 1.5 percent.
10. The engine coolant temperature (ECT) is between 70-109°C (158-228°F).
11. The intake air temperature (IAT) is between -7 and +105°C (+19 and +221°F).
12. The barometric pressure (BARO) is more than 72 kPa.
13. The calculated catalytic converter temperature is between 300-900°C (572-1,652°F).
14. The long term fuel trim is learned.
15. The engine idle time is less than 1 minute.
16. The vehicle speed is less than 3 km/h (2 mph).
17. DTC P0420 is ran one time per ignition cycle when the above conditions are met for more than 4.5 seconds.

The catalyst test is disable if the ECM detects one of the following conditions

1. The engine speed changes more than 80 RPM.
2. The A/C compressor clutch changes state.
3. The cooling fans change state.
4. Insufficient air/fuel ratio activity.

The ECM has determined the catalyst efficiency has degraded below a calibrated threshold.

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

1. 5: The MIL flashes if the ECM detects a catalyst damaging misfire. If the engine is misfiring, repair the misfire condition so catalyst damage does not occur.

DTC P0420

The evaporative emission (EVAP) small leak test applies vacuum to the EVAP system and monitors vacuum decay. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the vacuum decay rate. At an appropriate time, the EVAP canister purge valve and the EVAP vent valve are turned ON. This allows the engine to draw vacuum on the EVAP system. After the desired vacuum level has been achieved, the EVAP purge valve is turned OFF, sealing the system. A leak is detected by monitoring for a decrease in the vacuum level during a given time period. If the system detects a leak larger than a calibrated amount, DTC P0442 will set.

This diagnostic procedure supports the following DTC

DTC P0442 Evaporative Emissions (EVAP) Small Leak Detected

1. DTCs P0106, P0107, P0108, P112, P0113, P0117, P0118, P0122, P0123, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0201, P0202, P0203, P0204, P0300, P0402, P0404, P0405, P0406, P0443, P0452, P0453, P0462, P0463, P0488, P0502, P0506, P0507, P2195, and P2196 are not set.
2. The ignition 1 voltage is between 11-16 volts.
3. The barometric pressure (BARO) is more than 72 kPa.
4. The engine coolant temperature (ECT) and the intake air temperature (IAT) at start-up are between -5°C and +40°C (+23°F and +140°F).
5. The engine is OFF for more than 6 hours or the following conditions must be met: The start-up IAT minus start-up ECT are within 12°C (22°F). The start-up ECT minus start-up IAT is within 50°C (90°F).
6. The start-up IAT minus IAT are within 3°C (5°F).
7. The purge enable time is less than 360 seconds.
8. The engine run time is more than 1 second and less than 360 seconds.
9. The fuel level is between 24-94 percent.
10. The engine speed is less than 1,200 RPM.
11. The vehicle speed is less than 3 km/h (2 mph).
12. The throttle position is less than 1 percent.
13. DTC P0442 runs once an ignition cycle when the above conditions are met.

The EVAP system can achieve vacuum but a vacuum decay is detected 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.

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 . Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light. See 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.

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

1. 6: This step verifies that repairs are complete and that other conditions are not present.

DTC P0442

An ignition voltage is supplied directly to the evaporative emissions (EVAP) purge valve. The control module controls the EVAP purge valve by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply ground for the controlled component. The control module monitors the status of the driver. If the control module detects an incorrect voltage for the commanded state of the driver, DTC P0443 sets.

This diagnostic procedure supports the following DTC

DTC P0443 Evaporative Emissions (EVAP) Purge Solenoid Control Circuit

1. DTC P0606 is not set.
2. The ignition 1 voltage is more than 11 volts.
3. DTC P0443 runs continuously once the above conditions are met.

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match, for more 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.

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

1. 2: This step tests if the concern is active. The EVAP purge valve is pulse width modulated (PWM). When the purge valve is commanded to 50 percent, you should hear or feel a clicking. The clicking should stop when the EVAP purge valve is commanded to 0 percent. The rate at which the valve cycles should increase as the commanded state is increased. The rate should decrease when the commanded state is decreased. Repeat the commands as necessary.
2. 5: This step tests if a ground is constantly being applied to the EVAP purge valve.
3. 6: This step verifies that the ECM is providing ground to the EVAP purge valve.

DTC P0443

A restricted or blocked evaporative emission (EVAP) vent path is detected by the control module commanding the purge valve ON (open) and the vent valve ON (closed) allowing a vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the purge valve OFF (closed) and the vent valve OFF (open) while monitoring 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, DTC P0446 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 valves.

DTC P0446

This diagnostic procedure supports the following DTC

DTC P0446 Evaporative Emissions (EVAP) Vent System Performance

1. Before the engine control module (ECM) can report DTC P0446 failed, DTCs P0442, P0456, and P0496 must run and pass.
2. DTCs P0106, P0107, P0108, P112, P0113, P0117, P0118, P0122, P0123, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0201, P0202, P0203, P0204, P0300, P0402, P0404, P0405, P0406, P0443, P0452, P0453, P0462, P0463, P0488, P0502, P0506, P0507, P2195, and P2196 are not set.
3. The ignition 1 voltage is between 11-16 volts.
4. The barometric pressure (BARO) is more than 72 kPa.
5. The engine coolant temperature (ECT) and the intake air temperature (IAT) at start-up are between -5°C and +40°C (23°F and 140°F).
6. The purge enable time is less than 360 seconds.
7. The fuel level is between 24-94%.
8. The start-up IAT minus the startup ECT is within 12°C (22°F).
9. The start-up ECT minus startup IAT is within 50°C (90°F).
10. DTC P0446 runs once an ignition cycle when the above conditions are met.

1. Fuel tank pressure is more than 9.3 mm Hg (5 inch H2O) or less than -4.7 mm Hg (-2.5 inch H2O) at cold engine startup.
2. The above condition is present for at least 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.

An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP vent valve inlet or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill problem.

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

1. 4: This test determines if the FTP sensor is operating correctly.

DTC P0446

An ignition voltage is supplied directly to the evaporative emission (EVAP) canister vent valve. The control module controls the EVAP vent valve by grounding the control circuit via an internal driver switch. The primary function of the driver is to supply ground for the controlled component. The control module monitors the status of the driver. If the control module detects an incorrect voltage for the commanded state of the driver, DTC P0449 sets.

This diagnostic procedure supports the following DTC

DTC P0449 Evaporative Emissions (EVAP) Vent Solenoid Control Circuit

1. DTC P0606 is not set.
2. The ignition 1 voltage is more than 11 volts.
3. DTC P0449 runs continuously once the above conditions are met.

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match, for more than 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 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. 2: A click should be heard or felt when the valve operates. Ensure that both the ON and the OFF states are commanded. Repeat the commands as necessary.
2. 5: This step verifies that the ECM is providing ground to the EVAP vent valve.
3. 6: This step tests if the EVAP vent valve control circuit is grounded.

DTC P0449

The evaporative emission (EVAP) system is used to store fuel vapors in order to reduce the amount of fuel vapors into the atmosphere. The fuel tank pressure (FTP) sensor is only used for EVAP system diagnostics. The FTP sensor is a transducer that varies resistance according to changes in the fuel tank pressure. The engine control module (ECM) monitors the FTP sensor signal in order to detect vacuum decay and excess vacuum during the EVAP system diagnostic test. The ECM supplies a 5 volt reference and a low reference circuit to the FTP sensor. If the ECM detects that the FTP sensor signal voltage is too low, this DTC sets.

The following table illustrates the relationship between 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

The ignition is ON, or the engine is running.

DTC P0452 runs continuously.

The FTP sensor voltage is less than 0.2 volt, for more than 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 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. 4: This step tests for the proper operation of the circuit.

DTC P0452

The evaporative emission (EVAP) system is used to store fuel vapors in order to reduce the amount of fuel vapors into the atmosphere. The fuel tank pressure (FTP) sensor is only used for EVAP system diagnostics. The FTP sensor is a transducer that varies resistance according to changes in the fuel tank pressure. The engine control module (ECM) monitors the FTP sensor signal in order to detect vacuum decay and excess vacuum during the EVAP system diagnostic test. The ECM supplies a 5-volt reference and a low reference circuit to the FTP sensor. If the ECM detects that the FTP sensor signal voltage is too high, 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

The ignition is ON, or the engine is running.

DTC P0453 runs continuously.

The FTP sensor voltage is more than 4.8 volt, for more than 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 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. 2: This step determines if the condition is present.

1. 4: This step tests the signal circuit of the FTP sensor.
2. 5: This step tests the ground circuit of the FTP sensor.
3. 6: This step tests the 5-volt reference circuit of the FTP sensor.

DTC P0453

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 valve OPEN and the EVAP vent 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 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 the vacuum level increases too slowly, 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 valves.

DTC P0455

This diagnostic procedure supports the following DTC

DTC P0455 Evaporative Emission (EVAP) System Large Leak Detected

1. DTCs P0106, P0107, P0108, P112, P0113, P0117, P0118, P0122, P0123, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0201, P0202, P0203, P0204, P0300, P0402, P0404, P0405, P0406, P0443, P0452, P0453, P0462, P0463, P0488, P0502, P0506, P0507, P2195, and P2196 are not set.
2. The ignition 1 voltage is between 11-16 volts.
3. The barometric pressure (BARO) is more than 72 kPa.
4. The start-up IAT minus the startup ECT is within 12°C (22°F).
5. The start-up ECT minus startup IAT is within 50°C (90°F).
6. The engine coolant temperature (ECT) and the intake air temperature (IAT) at start-up are between -5°C and +40°C (23°F and 140°F).
7. The start-up IAT minus IAT are within 3°C (5°F).
8. The purge enable time is less than 360 seconds.
9. The engine run time is more than 1 second and less than 420 seconds.
10. DTC P0455 runs once an ignition cycle when the above conditions are met.

The ECM detects 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/aveo/i-2003-2008/remont/testing-diagnostics/#engine-controls-16l-l91-introduction__special-tools) . Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light. See «Special Tools»(/chevrolet/aveo/i-2003-2008/remont/testing-diagnostics/#engine-controls-16l-l91-introduction__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 purge solenoid, 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/aveo/i-2003-2008/remont/testing-diagnostics/#engine-controls-16l-l91-introduction__special-tools) .
4. Observe the Freeze Frame/Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition occurs that caused the DTC to set. This may assist in diagnosing the condition.
5. For an intermittent condition, refer to «Intermittent Conditions»(/chevrolet/aveo/i-2003-2008/remont/testing-diagnostics/#engine-controls-16l-l91-troubleshooting-diagnosis__intermittent-conditions) .

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

1. 4: 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. 6: This step verifies proper operation of the FTP sensor.
3. 7: A normal operating FTP sensor should increase above 5 inches H20 and stop between 6 inches H20 and 7 inches H20.
4. 9: This step tests the EVAP purge solenoid vacuum source between the EVAP purge solenoid and the Intake manifold for restrictions or blockages.

DTC P0455 Evaporative Emission (EVAP) System Large Leak Detected

See also:
• Fuel Injector Coil Test
• Intermittent Conditions
• Engine Controls Schematics
• Engine Controls Connector End Views
• Diagnostic System Check - Engine Controls
• Probing Electrical Connectors
• Circuit Testing
• Wiring Repairs
• Testing for Intermittent Conditions and Poor Connections
• Connector Repairs
• Diagnostic Trouble Code (DTC) List
• Symptoms - Engine Cooling
• DTC P0117
• Loss of Coolant
• Thermostat Diagnosis
• CKP System Variation Learn Procedure
• Power Distribution Schematics
• Restricted Exhaust
• Using Connector Test Adapters
• Measuring Voltage Drop
• Diagnostic System Check - ABS
• Testing for a Short to Voltage
• Measuring Frequency
• Testing for Short to Ground
• Repairing Connector Terminals
• Special Tools
• Lifting and Jacking the Vehicle
• Using Fused Jumper Wires
• Measuring Voltage
• Repairing Damaged Wire Insulation
• DTC P0420