Engine Controls - 2.6l & 3.2l - Diagnosis (DTC p0172 - p0446) Cadillac CTS I

Circuit Description

The engine control module (ECM) controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy and emission control. Fuel delivery is controlled differently during Open and Closed Loop. During Open Loop the ECM determines fuel delivery based on sensor signals, without oxygen sensor input. During Closed Loop, the oxygen sensor inputs are added and used by the ECM to calculate fuel trim. If the oxygen sensors indicate a lean condition, fuel trim values will be above 0 percent. If the oxygen sensors indicate a rich condition, fuel trim values will be below 0 percent. Short Term Fuel Trim (FT) values change rapidly in response to the heated oxygen sensor (HO2S) voltage signals. Long Term FT values change slower in response to trends in Short Term FT adjustments. The fuel trim diagnostic will conduct a test to determine if a rich failure actually exists or if excessive vapor from the evaporative emission (EVAP) canister is causing a rich condition. If the ECM detects excessive vapor then a pass is logged. This DTC is continuously monitored during operation. If the ECM detects an excessively rich condition, DTC P0172 or P0175 sets.

Conditions for Running the DTC

1. DTCs P0101, P0102, P0103, P0130, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, are not set.
2. The system is in Closed Loop status.
3. Fuel trim is enabled.
4. The fuel level is more than 10 percent.

Conditions for Setting the DTC

1. The LT FT Cruise/Acce parameter is below -23 percent. OR
2. THE LT FT Idle/Decel. parameter is below -8.5 percent.

Action Taken When the DTC Sets

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.

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. A skewed mass air flow (MAF) sensor may set this DTC.
2. Fuel contamination, such as water and alcohol will effect fuel trim.
3. Review Failure Records with a scan tool. If intermittent condition is suspected, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-troubleshooting__intermittent-conditions) .

DTC P0172 or P0175

The engine control module (ECM) enables the appropriate fuel injector on the intake stroke for each cylinder. Ignition voltage is supplied directly 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 ECM detects an incorrect voltage for the commanded state of the driver, a fuel injector control DTC sets.

1. The engine speed is more than 40 RPM.
2. The system voltage is between 8-18 volts.

1. The ECM detects an open on the fuel injector control circuit.
2. The condition exists for 30 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. Performing the Fuel Injector Coil Test may help isolate an intermittent condition. Refer to «Fuel Injector Coil Test»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-troubleshooting) .
2. If the condition is intermittent, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-troubleshooting__intermittent-conditions) .

Test Description

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

1. 2: This step verifies that the condition is present.
2. 4: This step verifies that the ECM is able to control the fuel injector. If the test lamp flashes, the control module and the wiring are OK.
3. 5: This step isolates the circuit between the multi-way connector and the control module. An open on the fuel injector control circuit will not allow the test lamp to flash.
4. 7: This step inspects for fuel injector harness damage between the multi-way connector and the intake plenum. Careful inspection may isolate the condition before removal of the intake plenum.

DTC P0201-P0206

Description

This DTC is used to indicate that the engine speed exceeded the fuel cutoff limit in gear. This DTC may set if the transmission is placed in a low gear while driving down a steep grade or traveling at a high speed.

The engine is running.

The ECM detects the engine speed is more than 7,000 RPM for more 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.

DTC P0219

The throttle position (TP) sensors 1 and 2 are located within the throttle body assembly. The TP sensors share a common 5-volt reference circuit and a common low reference circuit. The 5-volt reference circuit is also shared with accelerator pedal position (APP) sensor 2. The 5-volt reference voltage is supplied on 2 separate engine control module (ECM) terminals, but the terminals are connected internally to the same voltage supply. Each TP sensor has an individual signal circuit, which provides the ECM with a signal voltage proportional to throttle the plate movement. When the throttle plate is in the closed position, the TP sensor 1 signal voltage is near the low reference and increases as the throttle plate is opened. TP sensor 2 signal voltage at closed throttle is near the 5-volt reference and decreases as the throttle plate is opened. The ECM compares the signal of the TP sensors to the mass air flow (MAF) sensor when the engine is running to determine if the sensor readings are correct. The control module also compares the signal of the TP sensor 1 and TP sensor 2 through the entire range. If the ECM detects a difference of more than 6 percent between sensor 1 and sensor 2, and a difference from the predicted range by more than 9 percent, DTC P0221 sets.

1. The battery voltage is more than 10 volts.
2. The TP voltage is more than 0.17 volt and less than 4.6 volts.
3. The engine speed is more than 1,320 RPM.

1. The TP sensor 1 disagrees more than 6 percent from TP sensor 2.
2. The TP sensor 2 disagrees more than 9 percent from the predicted value.
3. The above conditions are met for 280 milliseconds.

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 P0221

The throttle position (TP) sensors 1 and 2 are located within the throttle body assembly. The TP sensors share a common 5-volt reference circuit and a common low reference circuit. The 5-volt reference circuit is also shared with accelerator pedal position (APP) sensor 2. The 5-volt reference voltage is supplied on 2 separate engine control module (ECM) terminals, but the terminals are connected internally to the same voltage supply. Each TP sensor has an individual signal circuit, which provides the ECM with a signal voltage proportional to throttle the plate movement. When the throttle plate is in the closed position, the TP sensor 1 signal voltage is near the low reference and increases as the throttle plate is opened. TP sensor 2 signal voltage at closed throttle is near the 5-volt reference and decreases as the throttle plate is opened. If the ECM detects the TP sensor 2 signal voltage is less than 0.195 volt, DTC P0222 sets.

1. The battery voltage is more than 10 volts.
2. The engine speed is more than 1,320 RPM.

The TP sensor 2 voltage is less than 0.195 volt for more than 140 milliseconds.

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. 4: The ECM performs a comparison of the signals from both TP sensors during the entire range of operation. If the DTC does not set with the key ON and the accelerator pedal released, actuation the throttle may cause the DTC to set.
2. 10: The 5-volt reference for the TP sensors and the APP sensor 2 are connected inside the ECM. This step is to determine if the APP sensor is affecting the 5-volt reference circuit of the TP sensors.

DTC P0222

The throttle position (TP) sensors 1 and 2 are located within the throttle body assembly. The TP sensors share a common 5-volt reference circuit and a common low reference circuit. The 5-volt reference circuit is also shared with accelerator pedal position (APP) sensor 2. The 5-volt reference voltage is supplied on 2 separate engine control module (ECM) terminals, but the terminals are connected internally to the same voltage supply. Each TP sensor has an individual signal circuit, which provides the ECM with a signal voltage proportional to throttle the plate movement. When the throttle plate is in the closed position, the TP sensor 1 signal voltage is near the low reference and increases as the throttle plate is opened. TP sensor 2 signal voltage at closed throttle is near the 5-volt reference and decreases as the throttle plate is opened. If the ECM detects the TP sensor 2 signal voltage is more than 4.6 volts, DTC P0223 sets.

1. The battery voltage is more than 10 volts.
2. The engine speed is more than 1,320 RPM.

The TP sensor 2 voltage is more than 4.6 volt for more than 140 milliseconds.

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 P0223

The engine control module (ECM) enables the appropriate fuel injector on the intake stroke 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 ECM detects a short to ground for the commanded state of the driver, a fuel injector control DTC sets.

1. The engine speed is more than 40 RPM.
2. The system voltage is between 8-18 volts.

1. The ECM detects low voltage condition on the fuel injector control circuit.
2. The condition exists for 30 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. Performing the Fuel Injector Coil Test may help isolate an intermittent condition. Refer to «Fuel Injector Coil Test»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-troubleshooting) .
2. If the condition is intermittent, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-troubleshooting__intermittent-conditions) .

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

1. 2: This step verifies that the condition is present.
2. 4: This step isolates the condition. If the test lamp is illuminated the fuel injector control circuit is shorted to ground between the multi-way connector and the ECM.
3. 5: This step tests for a short to ground in the fuel injector control circuit between the multi-way connector and the affected fuel injector.
4. 6: This step isolates the circuit between the multi-way connector and the ECM.
5. 7: This step inspects for fuel injector harness damage between the multi-way connector and the intake plenum. Careful inspection may isolate the condition before removal of the intake plenum.

DTC P0261, P0264, P0267, P0270, P0273, or P0276

The engine control module (ECM) enables the appropriate fuel injector on the intake stroke for each cylinder. An 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 ECM detects a short to voltage for the commanded state of the driver, a fuel injector control DTC sets.

1. The engine speed is more than 40 RPM.
2. The system voltage is between 8-18 volts.

1. The ECM detects a high voltage condition on the fuel injector control circuit.
2. The condition exists for 30 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. Performing the Fuel Injector Coil Test may help isolate an intermittent condition. Refer to «Fuel Injector Coil Test»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-troubleshooting) .
2. If the condition is intermittent, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-troubleshooting__intermittent-conditions) .

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

1. 4: This step tests for a short to voltage on the fuel injector control circuit.
2. 6: This step inspects for fuel injector harness damage between the multi-way connector and the intake plenum. Careful inspection may isolate the condition before removal of the intake plenum.
3. 7: This step isolates the control circuit between the multi-way connector and the fuel injector. A short to voltage on the fuel injector control circuit will set this DTC.

DTC P0262, P0265, P0268, P0271, P0274, or P0277

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 3-way catalytic converter damage. The malfunction indicator lamp (MIL) will flash ON and OFF when the conditions for catalytic converter damage are present. DTCs 301 through 306 correspond to cylinders 1 through 6. If the ECM is able to determine that a specific cylinder is misfiring, the DTC for that cylinder will set. If the misfire rate is sufficient to cause emissions levels to exceed mandated standards, DTC P0300 will set.

1. DTCs P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, P0337, P0338, P0341, P0342, P0343, P0440, P0442, P0443, P0444 or P0445 are not set.
2. The engine speed is between 520-6,520 RPM.
3. The torque management is not active.
4. The anti-lock brake/traction control (ABS/TC) system is not active.
5. The ECM is not receiving a rough road signal.
6. The fuel cut-off is not active, including the traction control, the deceleration, the high speed/RPM.
7. The engine has been running for longer than 5 seconds.
8. The air intake temperature (IAT) is more than -8°C (17°F).

The ECM is detecting a crankshaft rotation speed variation indicating a misfire rate sufficient to cause emissions 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 ECM turns OFF the MIL after three consecutive drive trips that the diagnostic runs and does not fail within the same conditions that the DTC last failed.
2. A History DTC clears after forty consecutive warm-up cycles if no failures report by this diagnostic or any other emission related diagnostic.
3. The DTC can be cleared with a scan tool

A Misfire DTC could be caused by an excessive vibration from sources other than the engine. Check for the following possible sources

1. A tire or wheel that is out of round or out of balance
2. Variable thickness brake rotor or drum
3. An unbalanced drive shaft
4. Certain rough road conditions
5. a damaged accessory drive belt

DTC P0300 - Engine Misfire Detected

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 PCM is able to detect individual misfire events. A misfire rate that is high enough can cause 3-way catalytic converter damage. The malfunction indicator lamp (MIL) will flash ON and OFF when the conditions for catalytic converter damage are preset. DTCs P0301-P0306 correspond to cylinders 1-6. If the ECM is able to determine that a specific cylinder is misfiring, the DTC for that cylinder will set.

1. DTCs P0121, P0122, P0123, P0222, P0223, P0335, P0336, P0337, P0338, P0341, P0342, P0343, P0440, P0443, P0444, or P0445 are not set.
2. The engine speed is between 520-6,520 RPM.
3. The torque management is not active.
4. The anti-lock brake/traction control (ABS/TC) system is not active.
5. The ECM is not receiving a rough road signal.
6. The fuel cut-off is not active, including the traction control, the deceleration, the high speed/RPM.
7. The engine has been running for longer than 5 seconds.
8. The intake air temperature (IAT) is more than -8°C (17°F).

The ECM is detecting a crankshaft rotation speed variation indicating a single cylinder misfire rate sufficient to cause emissions levels to exceed mandated standard.

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 ECM turns OFF the MIL after three consecutive drive trips that the diagnostic runs and does not fail within the same conditions that the DTC last failed.
2. A History DTC clears after forty consecutive warm-up cycles if no failures report by this diagnostic or any other emission related diagnostic.
3. The DTC can be cleared with a scan tool

A misfire DTC could be caused by an excessive vibration from sources other than the engine. Check for the following possible sources

1. Tire or wheel out of round or balance
2. Variable thickness brake rotor or drum
3. Drive shaft not balanced
4. Certain rough road conditions
5. Damaged accessory drive belt

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

1. 2: DTCs that may cause a misfire DTC to set may include those for injector control circuits, oxygen sensors, the EVAP system, or fuel trim.
2. 9: This test is to determine if there is a problem in the heated oxygen sensor (HO2S) or wiring that is causing the ECM to alter the fuel trim. When the sensors are disconnected, the fuel system should go into Open Loop.

DTC P0301-P0306

Rough roads cause torque on the tires that is transmitted to the powertrain. This slows down the crankshaft giving the appearance of a misfire. The electronic brake control module (EBCM) determines rough road surfaces using input from the wheel speed sensors. The EBCM then sends the rough road data to the engine control module (ECM) via class 2 serial data. The data allows the ECM to distinguish the crankshaft speed variations caused by rough road surfaces from those caused by true misfires. If a loss of communication occurs that causes the PCM not to receive rough road information while a misfire condition is requesting the malfunction indicator lamp (MIL), DTC P0318 will set.

DTC P0300 is occurring and requesting the MIL to be illuminated.

The PCM is detecting a loss of communication with the EBCM for approximately 12 seconds or more.

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.

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

1. 2: This step ensures that the EBCM is capable of transmitting serial data on the class 2 serial data circuit.

DTC P0318

The knock sensor (KS) system is used in order to detect any engine detonation, or spark knock. The engine control module (ECM) will retard the spark timing based on the signals from the KS. The KS produces an AC voltage that is sent to the ECM. The amount of AC voltage produced is proportional to the amount of knock.

An operating engine produces a normal amount of engine mechanical vibration, or noise. The knock sensors will produce an AC voltage signal from this noise. When the engine is operating, the ECM will learn the minimum and maximum amplitude of the noise the engine produces. If the ECM will not allow proper diagnosis of the KS system, DTC P0324 will set.

1. The engine coolant temperature (ECT) is more than 40°C (104°F).
2. The engine speed is between 1,000-5,520 RPM
3. The volumetric efficiency is more than 40 percent.

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

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) system is used in order to detect any engine detonation, or spark knock. The engine control module (ECM) will retard the spark timing based on the signals from the KS. The knock sensors produce an AC voltage that is sent to the ECM. The amount of AC voltage produced is proportional to the amount of knock.

An operating engine produces a normal amount of engine mechanical vibration, or noise. The KS will produce an AC voltage signal from this noise. When the engine is operating, the ECM will learn the minimum and maximum amplitude of the noise the engine produces. If the ECM detects that this amplitude is below the normal operating range, DTC P0327 or P0332 will set.

1. The engine coolant temperature (ECT) sensor is more than 40°C (104°F).
2. The engine speed is more than 2000 RPM.
3. The volumetric efficiency is more than 40 percent.

The KS signal is below the normal operating range or the KS signal is not present.

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. The KS must be torqued correctly. Refer to «Knock Sensor (KS) 1 Replacement»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-introduction) and «Knock Sensor (KS) 2 Replacement»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-introduction) .
2. The mounting between the sensor and engine must be free of burrs, casting flash, and foreign material.
3. The KS head must be clear from hoses, brackets, and engine wiring.
4. If the KS is dropped, the KS must be replaced.
5. If the sensor lead is damaged in any way, the sensor must be replaced.
6. For an intermittent condition, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-troubleshooting__intermittent-conditions) .

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

1. 3: This step tests for continuity in the KS circuit. An out of limit (OL) on the DMM display indicates an open in either the wiring or the ECM.

DTC P0327 or P0332

The knock sensor (KS) system is used in order to detect any engine detonation, or spark knock. The engine control module (ECM) will retard the spark timing based on the signals from the KS. The KS produce an AC voltage that is sent to the ECM. The amount of AC voltage produced is proportional to the amount of knock.

An operating engine produces a normal amount of engine mechanical vibration, or noise. The KS will produce an AC voltage signal from this noise. When the engine is operating, the ECM will learn the minimum and maximum amplitude of the noise the engine produces. When the ECM determines that this amplitude is above the normal operating range, DTC P0328 or P0333 will set.

1. The engine coolant temperature (ECT) sensor is more than 40°C (104°F).
2. The engine speed more than 2,000 RPM.
3. The volumetric efficiency is more than 40 percent.

The KS signal is above the normal operating range.

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. The KS must be torqued correctly. Refer to «Knock Sensor (KS) 1 Replacement»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-introduction) and «Knock Sensor (KS) 2 Replacement»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-introduction) .
2. The mounting between the sensor and engine must be free of burrs, casting flash, and foreign material.
3. The KS head is clear from hoses, brackets, and engine wiring.
4. If the KS is dropped, the KS must be replaced.
5. If the sensor lead is damaged in any way, the sensor must be replaced.
6. If there is any excessive engine mechanical noise, the DTC may set.
7. For an intermittent condition, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-troubleshooting__intermittent-conditions) .

DTC P0328 or P0333

The crankshaft position (CKP) sensor signal indicates the crankshaft speed and position. The CKP sensor works in conjunction with a 58-rib reluctor ring attached to the crankshaft in which two ribs are missing, 60 minus 2 ring. The engine control module (ECM) synchronizes the CKP by the reference gap which is created by the two missing ribs. The CKP sensor circuits connect directly to the ECM. The circuits between the CKP sensor and the ECM consists of the following circuits

1. A CKP sensor high
2. A CKP sensor low
3. A shielded ground

If the ECM has detected no CKP sensor pulses, DTC P0335 sets.

1. The engine is cranking or running.
2. DTCs P0341, P0342, P0343 are not set.

The ECM has detected no CKP sensor pulses.

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. 4: This step tests for a short to voltage in a CKP sensor circuit between the ECM connector and the CKP connector when the key is off.
2. 5: This step tests for a short to voltage in a CKP sensor circuit and an ignition circuit between the ECM connector and the CKP connector.

DTC P0335

The crankshaft position (CKP) sensor signal indicates the crankshaft speed and position. The CKP sensor works in conjunction with a 58-rib reluctor ring attached to the crankshaft in which two ribs are missing, 60 minus 2 ring. The engine controls module (ECM) synchronizes the crankshaft position by the reference gap which is created by the two missing ribs. The CKP sensor circuits are connected directly to the ECM. The circuits between the CKP sensor and the ECM consists of the following circuits

1. A CKP sensor high
2. A CKP sensor low
3. A shielded ground

If the ECM has detected no CKP reference sync gap, DTC P0336 sets.

1. The engine is cranking or running.
2. DTCs P0341, P0342, P0343 are not set.

The ECM has detected no CKP reference sync gap.

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 works in conjunction with a 58-rib reluctor ring attached to the crankshaft in which two ribs are missing, 60 minus 2 ring. The engine control module (ECM) synchronizes the crankshaft position by the reference gap which is created by the two missing ribs. The CKP sensor circuits are connected directly to the ECM. The circuits between the CKP sensor and the ECM consists of the following

1. A CKP sensor high
2. A CKP sensor low
3. A shielded ground

If the ECM has detected less than 58 reference pulses, DTC P0337 sets.

1. The engine is cranking or running.
2. DTCs P0341, P0342, P0343 are not set.

The ECM has detected less than 58 CKP reference pulses.

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. 4: This step tests for resistance of the CKP sensor and its lead.
2. 5: This step inspects for electromagnetic interference in any of the CKP circuits.

DTC P0337

The crankshaft position (CKP) sensor signal indicates the crankshaft speed and position. The CKP sensor works in conjunction with a 58-rib reluctor ring attached to the crankshaft in which two ribs are missing, 60 minus 2 ring. The engine control module (ECM) synchronizes the crankshaft position by the reference gap which is created by the two missing ribs. The CKP sensor circuits are connected directly to the ECM. The circuits between the CKP sensor and the ECM consists of the following circuits

1. A CKP sensor high
2. A CKP sensor low
3. A shielded ground

If the ECM has detected more than 58 reference pulses, DTC P0338 sets.

1. The engine is cranking or running.
2. DTCs P0341, P0342, P0343 are not set.

The ECM has detected more than 58 reference pulses.

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. 4: This step tests for resistance of the CKP sensor and its lead.
2. 5: This step inspects for electromagnetic interference in any of the CKP circuits.

DTC P0338

The camshaft position (CMP) sensor is a hall effect switching device that works in conjunction with a single tooth reluctor wheel used to determine the position of the bank 2 exhaust camshaft. The engine control module (ECM) expects the CMP sensor signal to be low, 0 volts, as the single tooth in the reluctor wheel passes the sensor, and high, 12 volts, during the remainder of the reluctor wheel rotation. The ECM supplies a 12-volt pull up voltage on the CMP sensor signal circuit. The ECM expects to see one transition from high to low every two crankshaft revolutions. This signal, when combined with the crankshaft position (CKP) sensor signal, enables the ECM to properly synchronize ignition timing, fuel delivery and knock control. As long as the CKP signal is available, the engine can start and run. The ECM will default to a non-sequential fuel injector operation even if there is no CMP sensor signal. If the ECM detects extra or missing CMP sensor signal transitions within a certain number of crankshaft revolutions, DTC P0341 sets.

The CMP sensor has the following circuits

1. Ignition 1 voltage circuit
2. Low Reference circuit
3. CMP sensor signal circuit

The engine is running.

The CMP signal is inconsistent for eight or more crankshaft revolutions.

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. The following conditions may cause this DTC to set: Camshaft reluctor wheel damage Incorrect sensor installation The sensor coming in contact with the reluctor wheel Excessive air gap between the reluctor wheel and the sensor magnet A cracked or damaged sensor Foreign material passing between the sensor and the reluctor wheel
2. This DTC will set with an intermittent failure on the ignition 1 voltage circuit, the CMP sensor signal circuit, or the low reference circuit. A hard failure of any one of these circuits should set DTC P0342 or P0343.
3. The CMP sensor low reference circuit is shared with the mass air flow (MAF) sensor, and the engine coolant temperature (ECT) sensor.

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

1. 2: This step inspects for electromagnetic interference (EMI) on the CMP sensor circuits.

DTC P0341

The camshaft position (CMP) sensor is a hall effect switching device that works in conjunction with a single tooth reluctor wheel used to determine the position of the bank 2 exhaust camshaft. The engine control module (ECM) expects the CMP sensor signal to be low, 0 volts, as the single tooth in the reluctor wheel passes the sensor, and high, 12 volts, during the remainder of the reluctor wheel rotation. The ECM supplies a 12-volt pull up voltage on the CMP sensor signal circuit. The ECM expects to see one transition from high to low every two crankshaft revolutions. This signal, when combined with the crankshaft position (CKP) sensor signal, enables the ECM to properly synchronize ignition timing, fuel delivery and knock control. As long as the CKP signal is available, the engine can start and run. The ECM will default to a non-sequential fuel injector operation even if there is no CMP sensor signal. If the ECM detects continuously low signal transitions within a certain number of crankshaft revolutions, DTC P0342 sets.

The CMP sensor has the following circuits

1. Ignition 1 voltage circuit
2. Low Reference circuit
3. CMP sensor signal circuit

The engine is running.

The CMP sensor signal is continuously low for eight or more crankshaft revolutions.

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. The following conditions may cause this DTC to set: Camshaft reluctor wheel damage Incorrect sensor installation The sensor coming in contact with the reluctor wheel Excessive air gap between the reluctor wheel and the sensor magnet A cracked or damaged sensor Foreign material passing between the sensor and the reluctor wheel
2. The CMP sensor low reference circuit is shared with the Mass Air Flow (MAF) sensor, and the Engine Coolant Temperature (ECT) sensor.
3. If an intermittent condition exists, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-troubleshooting__intermittent-conditions) .

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

1. 2: This step verifies that the fault is present.
2. 4: This step tests the CMP sensor signal circuit. Applying a ground causes the CMP signal Active Counter to increment when its touched if the circuit and the ECM are operating properly.
3. 5: This step measures the resistance of the CMP sensor signal circuit.

DTC P0342

The camshaft position (CMP) sensor is a hall effect switching device that works in conjunction with a single tooth reluctor wheel used to determine the position of the bank 2 exhaust camshaft. The engine control module (ECM) expects the CMP sensor signal to be low, 0 volts, as the single tooth in the reluctor wheel passes the sensor, and high, 12 volts, during the remainder of the reluctor wheel rotation. The ECM supplies a 12-volt pull up voltage on the CMP sensor signal circuit. The ECM expects to see one transition from high to low every two crankshaft revolutions. This signal, when combined with the crankshaft position (CKP) sensor signal, enables the ECM to properly synchronize ignition timing, fuel delivery and knock control. As long as the CKP signal is available, the engine can start and run. The ECM will default to a non-sequential fuel injector operation even if there is no CMP sensor signal. If the ECM detects continuously high signal transitions within a certain number of crankshaft revolutions, DTC P0343 sets.

The CMP sensor has the following circuits

1. Ignition 1 voltage circuit
2. Low reference circuit
3. CMP sensor signal circuit

The engine is running.

The CMP sensor signal is continuously high for eight or more crankshaft revolutions.

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. The following conditions may cause this DTC to set: Camshaft reluctor wheel damage The sensor for proper installation The sensor coming in contact with the reluctor wheel Excessive air gap between the reluctor wheel and the sensor magnet A cracked or damaged sensor Foreign material passing between the sensor and the reluctor wheel
2. If an intermittent condition exists, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-troubleshooting__intermittent-conditions) .

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

1. 2: This step verifies that the fault is present.
2. 5: This step determines if the fault is in the ignition 1 voltage circuit or the low reference circuit.
3. 6: This step tests the CMP sensor signal circuit. Applying a ground causes the CMP signal Active Counter to increment when the circuit is touched if the circuit and the ECM are operating properly.

DTC P0343

A three-way catalytic converter (TWC) 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 CO that are present in the exhaust gas. This process converts these chemicals into water vapor and carbon dioxide (CO2), and will reduce the NOx, converting the NOx into nitrogen.

The catalytic converter stores oxygen. The efficiency of the TWC is determined by the measurement of the oxygen storage capacity (OSC). The engine control module (ECM) measures the catalyst OSC by monitoring the heated oxygen sensor (HO2S) bank 1 sensor 2 and HO2S bank 2 sensor 2, during a steady state cruise. The ECM commands the air-to-fuel ratio lean and then rich for a calibrated number of cycles while monitoring the response time of the HO2S 2. The ECM then establishes an average response time from subsequent air-to-fuel ratio cycles. The difference of the average response time determines the OSC of the catalyst. If the ECM detects low TWC efficiency DTC P0420 for bank 1 or DTC P0430 for bank 2 sets.

DTC Descriptors

This diagnostic procedure supports the following DTCs

1. DTC P0420 Catalyst System Low Efficiency Bank 1
2. DTC P0430 Catalyst System Low Efficiency Bank 2

1. DTCs P0030-P0032, P0031, P0036, P0037, P0038, P0050-P0052, P0051, P0056-P0058, P0057, P0101, P0102, P0103, P0121, P0122, P0123, P0125, P0128, P0130, P0131, P0132, P0133, P0134, P0135, P0136, P0138, P0140, P0137-P0141, P0150-P0158, P0160, P0161, P0171, P0172, P0174, P0175, P0221, P0222, P0223, P0300-P0306, P0313, P0335, P0336, P0340, P0341, P0440, P0442-P0449, P0451, P0452, P0453, P0455, P0458, P0459, P0496, or P0500 are not set.
2. The engine has been running for more than 10 minutes.
3. The engine speed is between 1,200-3,000 RPM.
4. The calculated catalyst temperature is between 520-720°C (968-1,454°F).
5. The engine is in Closed Loop fuel control.
6. The vehicle speed sensor (VSS) is between 20-100 km/h (13-62 mph).
7. The engine is at a steady cruise, with no load variation.
8. The engine load is between 25-45 percent.
9. Before the ECM can report DTC P0420 or P0430 failed, the HO2S response test and HO2S heater response test have run and passed.
10. A drive cycle is completed once the above conditions are met.
11. DTCs P0420 and P0430 run continuously once the above conditions are met.

The PCM determines that the oxygen storage capability of the TWC has degraded to less than a calibrated threshold.

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. Fuel with a high sulfur content can cause inaccurate converter test results. Verify the fuel quality.
2. Certain conditions may cause a catalytic converter to degrade. These conditions may include the following: An engine misfire High engine oil or high coolant consumption Retarded spark timing A weak spark A lean fuel mixture A rich fuel mixture A damaged oxygen sensor wiring harness
3. Correct any condition that may cause an engine performance concern.
4. If an intermittent condition cannot be duplicated, the information included in Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC was set.

DTC P0420 or P0430

System Description

This diagnostic test the Evaporative Emission (EVAP) System for a small leak, when the key is turned OFF and the correct conditions are met.

Heat from the Exhaust System is transferred into a vehicle fuel tank while the vehicle is operating. When the vehicle is turned off a change in fuel tank vapor temperature occurs. With the EVAP System sealed, this results in corresponding pressure changes in the fuel tank vapor space. This change is monitored by the control module using the fuel tank pressure sensor input. The control module then makes a judgement on the integrity of the system. With a 0.51 millimeter (0.02 inch) leak in the system, the amount of pressure change observed is significantly less than that of a sealed system.

If the control module detects a pressure change less than a calibrated amount, DTC P0442 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 P0442

1. DTC P0117, P0118, P0125, P0443, P0449, P0451, P0452, P0453, P0455, P0458, P0459, P0496, P0498, P0499, P0500, P0560, P0562, P0563 are not set.
2. DTC P0455 must run and pass.
3. The start-up intake air temperature (IAT) is between 2-32°C (36-90°F).
4. The start-up engine coolant temperature (ECT) is less than 40°C (104°F).
5. The start-up IAT and ECT are within 8°C (15°F).
6. The barometric pressure (BARO) is more than 68 kPa.
7. The ambient air temperature is between 2-32°C (36-90°F).
8. The engine run time is a minimum of 10 minutes.
9. The vehicle has traveled more than 8.1 kilometers (5 miles) this trip.
10. The vehicle odometer shows more than 20 kilometers (12 miles).
11. The ECT is more than 75°C (176°F) at engine shut down.
12. The fuel level is between 15-85 percent.
13. The battery voltage is more than 11 volts.
14. The ignition is OFF.
15. The fuel level change with ignition OFF is less than 10 percent.

The control module detects a pressure change that is less than a calibrated amount.

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. Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light. 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. To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT High Intensity White Light.
3. If the condition is intermittent, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-26l-32l-troubleshooting__intermittent-conditions) .

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

1. 2: This step verifies that a failure condition is present.
2. 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.
3. 6: This step verifies that repairs are complete and that no other condition is present.

DTC P0442

An ignition voltage is supplied directly to the evaporative emission (EVAP) canister purge 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 3.5 volts on the control circuit while the driver is commanded OFF, this DTC sets.

1. The engine speed is more than 40 RPM.
2. The system voltage is between 8-18 volts.

1. The control module detects 3.5 volts on the EVAP canister purge solenoid valve control circuit with the driver commanded OFF.
2. The fault is present for 50 seconds, cumulative during the drive cycle.

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 canister purge solenoid valve is pulse width modulated (PWM). An audible clicking should be heard when the EVAP canister purge solenoid valve is commanded to 50 percent and should stop when the EVAP canister purge solenoid valve is commanded to 0 percent. The rate at which the valve cycles should increase as the commanded state is increased and decreased as the commanded state is decreased.
2. 4: This step tests for proper ignition voltage supply to the EVAP canister purge solenoid valve.
3. 5: This step tests the control modules ability to supply a ground to the EVAP canister purge solenoid valve.

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

1. DTC P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0221, P0222, P0223, P0440, P0442, P0443, P0449, P0451, P0452, P0453, P0458, P0459, P0496, P0498, P0499, P0500, P0560, P0562, P0563, P2122, P2123, P2127, P2128, P2138 are not set.
2. The battery voltage is between 10.5-18 volts.
3. The barometric pressure (BARO) is more than 68 kPa.
4. The fuel level is between 15-85 percent.
5. The engine coolant temperature (ECT) is between 4-65°C (39-149°F).
6. The intake air temperature (IAT) is between 2-32°C (36-90°F).
7. The start-up ECT and IAT are within 9°C (16°F) of each other.
8. The vehicle speed sensor (VSS) is 0 km/h (0 mph).
9. The fuel tank pressure is between -19 and +7.5 mm Hg (-10 and +4 in H2O).
10. The engine is idling.
11. The engine is operating in Closed Loop.

1. The FTP is less than -10 inches H2O.
2. The condition is present for 30 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 P0446

See also:
• Intermittent Conditions
• Diagnostic System Check - Engine Controls
• Emission Hose Routing Diagram
• Fuel System Diagnosis
• Symptoms - Engine Mechanical
• Diagnostic Trouble Code (DTC) List
• Engine Control Module (ECM) Connector End Views
• Engine Controls Connector End Views
• Circuit Testing
• Wiring Repairs
• Connector Repairs
• Testing for Continuity
• Testing for Intermittent Conditions and Poor Connections
• Engine Control Module (ECM) Replacement
• DTC P0101
• Diagnostic System Check - ABS
• Crankshaft and Bearings Removal
• Probing Electrical Connectors
• Exhaust Leakage
• Lifting and Jacking the Vehicle