Engine Controls - 5.7l - Diagnosis (DTC p0068 - p0174) Cadillac CTS I

Circuit Description

The powertrain control module (PCM) uses the throttle position (TP), barometric pressure (BARO), intake air temperature (IAT), and engine RPM in order to calculate the predicted mass airflow rate. The PCM compares the predicted mass air flow (MAF) value to the actual mass airflow value and the speed density calculation in order to verify the proper throttle operation. If the PCM detects that the difference between the actual air flow (MAF) and the speed density calculated air flow is greater than expected, DTC P0068 sets.

Conditions for Running the DTC

1. DTCs P0601, P0602, P0604, P0606, P1516, P2101, P2108, U0107 are not set.
2. DTCs P0120, P0220, and P2135 are not set at the same time or DTCs P0120 and P0220 are not set at the same time.
3. The engine operates longer than 1 second.
4. The engine speed is more than 500 RPM.

Conditions for Setting the DTC

1. The PCM detects that the difference between the actual airflow (MAF) and the speed density calculated airflow is greater than expected.
2. The above condition is met for less than 1 second.

Action Taken When the DTC Sets

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

Conditions for Clearing the MIL/DTC

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

Diagnostic Aids

1. Inspect the throttle blade for being broken, bent, or missing.
2. Inspect the TP sensor for proper installation. A sensor that is mis-aligned could set this DTC.
3. Inspect the TAC module connectors for signs of water intrusion. When water intrusion occurs, multiple DTCs could be set with no DTC circuit or component conditions found during diagnostic testing.
4. Physically and visually inspect the throttle body assembly, and correct any problems that you observe. Manually move the throttle blade from closed to wide open throttle (WOT). You should not need to use excessive force. The throttle blade should move smoothly through the full range and should return to a slightly open position on its own.
5. When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests that run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Keep this in mind when reviewing the stored information, Capture info.
6. For an intermittent condition, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-57l-troubleshooting__intermittent-conditions) .

Test Description

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

1. 5: When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests that run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Keep this in mind when reviewing the stored information, Capture info.

DTC P0068

The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The powertrain control module (PCM) uses the MAF sensor signal to provide the correct fuel delivery for all engine speeds and loads. A small quantity of air entering the engine indicates a deceleration or idle condition. A large quantity of air entering the engine indicates an acceleration or high load condition. The MAF sensor has the following circuits

1. An ignition 1 voltage circuit
2. A ground circuit
3. A signal circuit

The PCM applies a voltage to the sensor on the signal circuit. The sensor uses the voltage to produce a frequency based on the inlet air flow through the sensor bore. The frequency varies within a range of near 2,000 Hertz at idle to near 11,500 Hertz at maximum engine load. The PCM uses the following sensor inputs to calculate a predicted MAF value

1. The manifold absolute pressure (MAP) sensor
2. The intake air temperature (IAT) sensor
3. The engine coolant temperature (ECT) sensor
4. The engine speed (RPM)

The PCM compares the actual MAF sensor frequency signal to the predicted MAF value. This comparison will determine if the signal is stuck based on a lack of variation, or is too low or too high for a given operating condition. If the PCM detects the actual MAF sensor frequency signal is not within a predetermined range of the calculated MAF value DTC P0101 sets.

1. DTCs P0102, P0103, P0106, P0107, P0108, P0120, P0220, P0442, P0446, P0449, P0455, P0496 and P2135 are not set.
2. The engine is running.
3. The ignition 1 signal is between 11 and 18 volts.
4. The throttle position (TP) indicated angle is less than 95 percent.
5. The change in the TP indicated angle is less than 5 percent.
6. The MAP sensor is more than 17 kPa.
7. The change in the MAP sensor is less than 3 kPa.
8. The above conditions are met for 1.5 seconds.

The PCM detects that the actual MAF sensor frequency signal is not within a predetermined range of the calculated MAF value 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 harness of the MAF sensor to verify that it is not routed too close to the following components: The secondary ignition wires or coils Any solenoids Any relays Any motors
2. A low minimum air rate through the sensor bore at idle or during deceleration may cause this DTC to set. Inspect for the following conditions: Any deposits on the throttle plate or in the throttle bore Any vacuum leak downstream of the MAF sensor
3. Inspect for any contamination or debris on the sensing elements of the MAF sensor.
4. Inspect the air induction system for any water intrusion. Any water that reaches the MAF sensor will skew the sensor and may cause this DTC to set.
5. Inspect the secondary air injection system (AIR) for any water intrusion.
6. A wide open throttle acceleration from a stop should cause the MAF sensor parameter on the scan tool to increase rapidly. This increase should be from 5-12 g/s at idle to 200 g/s or more at the time of the 1-2 shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust system.
7. Inspect for a skewed or stuck ECT sensor.
8. A high resistance of 15 ohms or more on the ignition 1 voltage circuit may cause the DTC to set. A high resistance may cause a driveability concern before this DTC sets.
9. The barometric pressure that is used to calculate the predicted mass air flow value is initially based on the MAP sensor at key ON. When the engine is running the BARO value is continually updated near wide open throttle. A skewed MAP sensor will cause the calculated mass air flow value to be inaccurate and may result in a no start condition. The value shown for the MAP sensor parameter varies with the altitude. With the ignition ON and the engine OFF, 101 kPa is the approximate value near sea level. This value will decrease by approximately 3 kPa for every 305 meters (1,000 feet) of altitude.
10. A high resistance on the low reference circuit of the MAP sensor may cause this DTC to set.
11. A short to voltage on the 5 volt reference circuit of the MAP sensor may cause this DTC to set.

If the condition is intermittent, refer to Intermittent Conditions .

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

1. 5: This step will determine if the MAP sensor pressure is within the proper range for a given altitude.
2. 6: This step will determine if the MAP sensor voltage is within the proper range at idle.
3. 7: This step will determine if the MAP sensor responds properly to the change in manifold pressure.
4. 8: This step will determine if the throttle position (TP) sensors are operating properly.
5. 9: This step will determine if any mechanical faults have caused this DTC to set.
6. 10: This voltage drop will determine if high resistance has caused this DTC to set.

DTC P0101

The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The powertrain control module (PCM) uses the MAF sensor signal to provide the correct fuel delivery for all engine speeds and loads. A small quantity of air entering the engine indicates a deceleration or idle condition. A large quantity of air entering the engine indicates an acceleration or high load condition. The MAF sensor has the following circuits

1. An ignition 1 voltage circuit
2. A ground circuit
3. A signal circuit

The PCM applies a voltage to the sensor on the signal circuit. The sensor uses the voltage to produce a frequency based on inlet air flow through the sensor bore. The frequency varies within a range of near 2,000 Hertz at idle to near 11,500 Hertz at maximum engine load. If the PCM detects a frequency signal less than the possible range of a correctly operating MAF sensor DTC P0102 sets.

1. The engine is running for more than 2 seconds.
2. The engine speed is more than 400 RPM.
3. The ignition 1 signal is more than 8 volts.
4. The MAF sensor frequency is stable for more than 1 second.

The PCM detects that the MAF sensor frequency signal is less than 1,200 Hz. for more than 0.6 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 harness of the MAF sensor to verify that it is not routed too close to the following components: The secondary ignition wires or coils Any solenoids Any relays Any motors
2. Inspect for any contamination or debris on the sensing elements of the MAF sensor.
3. A wide open throttle acceleration from a stop should cause the MAF sensor parameter on the scan tool to increase rapidly. This increase should be from 7-12 g/s at idle to 200 g/s or more at the time of the 1-2 shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust system.
4. A high resistance of 15 ohms or more on the ignition 1 voltage circuit may cause this DTC to set. A high resistance may cause a driveability concern before this DTC sets.
5. A high resistance of 15 ohms or more on the ground circuit of the MAF sensor may cause this DTC to set. A high resistance may cause a driveability concern before this DTC sets.

If the condition is intermittent, refer to Intermittent Conditions .

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

1. 5: This step will determine if any mechanical faults have caused this DTC to set.
2. 7: This voltage drop test will determine if high resistance has caused this DTC to set.
3. 9: This step verifies the voltage signal from the PCM to the MAF sensor connector.
4. 10: This step tests the signal circuit of the MAF sensor for a short to another 5-volt reference circuit.
5. 11: This step will determine if the PCM is able to process the frequency signal that it receives from the MAF sensor.
6. 14: This step will determine which portion of the circuit or which component is shorted to ground.
7. 17: This step verifies that the signal circuit is not shorted to any other PCM circuit.

DTC P0102

The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The powertrain control module (PCM) uses the MAF sensor signal to provide the correct fuel delivery for all engine speeds and loads. A small quantity of air entering the engine indicates a deceleration or idle condition. A large quantity of air entering the engine indicates an acceleration or high load condition. The MAF sensor has the following circuits

1. An ignition 1 voltage circuit
2. A ground circuit
3. A signal circuit

The PCM applies a voltage to the sensor on the signal circuit. The sensor uses the voltage to produce a frequency based on the inlet air flow through the sensor bore. The frequency varies within a range of near 2,000 Hertz at idle to near 11,500 Hertz at maximum engine load. If the PCM detects a frequency signal more than the possible range of a correctly operating MAF sensor DTC P0103 sets.

1. The engine is running for more than 2 seconds.
2. The engine speed is more than 400 RPM.
3. The ignition 1 signal is more than 8 volts.
4. The MAF sensor frequency is stable for more than 1 second.

The PCM detects that the MAF sensor frequency signal is more than 13,500 Hertz for more than 1.2 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. Inspect the air induction system for any water intrusion. The water rapidly cools the hot sensing elements in the sensor causing a false indication of excessive air flow. Any water that reaches the MAF sensor will skew the sensor and may cause this DTC to set.
2. A poor connection in the ignition 1 voltage circuit of the MAF sensor may cause this DTC to set.

If the condition is intermittent, refer to Intermittent Conditions .

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

1. 3: This step tests for Electromagnetic Interference (EMI) on the signal circuit of the MAF sensor. A frequency reading with the MAF sensor disconnected indicates an EMI related fault or a poor connection at the PCM. Disconnecting the MAF sensor may set additional related DTCs.
2. 4: This step will determine if incorrect harness routing has caused this DTC to set.
3. 5: This step will determine if water intrusion has caused this DTC to set.

DTC P0103

The manifold absolute pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on the engine load. The MAP sensor has the following circuits

1. A 5-volt reference circuit
2. A low reference circuit
3. A MAP sensor signal circuit

The powertrain control module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The PCM, also, provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The PCM should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a wide-open throttle (WOT). The MAP sensor is also used in order to determine the barometric pressure (BARO). This occurs when the ignition switch is turned ON, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. The PCM monitors the MAP sensor signal for voltage outside of the normal range.

The PCM calculates a predicted value for the MAP sensor based on throttle position (TP) and engine speed. The PCM then compares the predicted value to the actual MAP sensor signal. If the PCM detects that the MAP sensor signal is not within the predicted range, DTC P0106 sets.

1. DTCs P0101, P0102, P0103, P0107, P0108, P0120, P0220, P0442, P0443, P0446, P0455, P1125, P1514, P1515, P1516, P1518, P2108, P2120, P2121, P2125, P2126, P2130, P2131, P2135 are not set.
2. The engine speed is between 400-5,000 RPM.
3. The change in engine speed is less than 125 RPM.
4. Traction control is not active.
5. The A/C compressor clutch is steady.
6. The power steering is stable.
7. The clutch switch state does not change.
8. The brake switch state does not change.
9. The above conditions are met for 1 second.

The PCM detects that the MAP sensor voltage is not within the predicted range for 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.

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

1. 4: This step tests the ability of the MAP sensor to correctly indicate BARO.
2. 6: This step tests the ability of the MAP sensor to respond to an increase in engine vacuum.
3. 8: This step tests for a proper MAP sensor pressure with an applied vacuum.

DTC P0106

The manifold absolute pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on the engine load. The MAP sensor has the following circuits

1. 5-volt reference circuit
2. Low reference circuit
3. MAP sensor signal circuit

The powertrain control module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The PCM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The PCM should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a wide open throttle (WOT). The MAP sensor is also used in order to determine the barometric pressure (BARO). This occurs when the ignition switch is turned ON, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. The PCM monitors the MAP sensor signal for voltage outside of the normal range.

If the PCM detects a MAP sensor signal voltage that is excessively low, DTC P0107 sets.

If the PCM detects a MAP sensor signal voltage that is excessively low, DTC P0107 sets.

1. DTCs P0120, P0220, P1125, P1514, P1515, P1516, P1518, P2108, P2120, P2121, P2125, P2126, P2130, P2131, P2135 are not set.
2. The engine is running.
3. The throttle angle is 0 percent when the engine speed is less than 800 RPM. OR
4. The throttle angle is more than 12.5 percent when the engine speed is more than 800 RPM.

The PCM detects that the MAP sensor voltage is less than 0.10 volt 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 number below refers to the step number on the diagnostic table.

1. 4: Operate the vehicle within the same conditions as when the DTC failed. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records can help to locate an intermittent condition.

DTC P0107

The manifold absolute pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on the engine load. The MAP sensor has the following circuits

1. 5-volt reference circuit
2. Low reference circuit
3. MAP sensor signal circuit

The powertrain control module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The PCM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The PCM should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a wide open throttle (WOT). The MAP sensor is also used in order to determine the barometric pressure (BARO). This occurs when the ignition switch is turned ON, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. The PCM monitors the MAP sensor signal for voltage outside of the normal range.

If the PCM detects a MAP sensor signal voltage that is excessively high, DTC P0108 sets.

1. DTCs P0120, P0220, P1125, P1514, P1515, P1516, P1518, P2108, P2120, P2121, P2125, P2126, P2130, P2131, P2135 are not set.
2. The engine has been running for a length of time that is determined by the start-up coolant temperature. The length of time ranges from 4 minutes at less than -30°C (-22°F) to 30 seconds at more than 30°C (86°F).
3. The throttle angle is less than 1 percent when the engine speed is less than 1,200 RPM. or
4. The throttle angle is less than 20 percent when the engine speed is more than 1,200 RPM.

The PCM detects that the MAP sensor voltage is more than 4.9 volts 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 for any vacuum leaks.
2. This DTC may set as the result of a misfire.
3. This DTC may set as the result of improper tension or alignment of the timing chain.
4. If this DTC is determined to be intermittent, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-57l-troubleshooting__intermittent-conditions) .

DTC P0108

The intake air temperature (IAT) sensor is a variable resistor. The IAT sensor has a signal circuit and a low reference circuit. The IAT sensor measures the temperature of the air entering the engine. The powertrain control module (PCM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit. When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance decreases. With high sensor resistance, the PCM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the IAT signal circuit. If the PCM detects an excessively low IAT signal voltage, indicating a high temperature, DTC P0112 sets.

1. DTCs P0502, P0503 are not set.
2. The engine run time is more than 45 seconds.
3. The vehicle speed sensor (VSS) indicates that the vehicle speed is more than 40 km/h (25 mph).

The PCM detects that the IAT sensor parameter is more than 128°C (262°F) for 5 seconds.

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

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

1. When the vehicle is at ambient temperature the IAT sensor and the ECT sensor should be relatively close to each other. Refer to «Temperature vs Resistance»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-57l-introduction__temperature-vs-resistance) .
2. If an intermittent condition is suspected, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-57l-troubleshooting__intermittent-conditions) .

DTC P0112

The intake air temperature (IAT) sensor is a variable resistor. The IAT sensor has a signal circuit and a low reference circuit. The IAT sensor measures the temperature of the air entering the engine. The powertrain control module (PCM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit. When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance decreases. With high sensor resistance, the PCM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the IAT signal circuit. If the PCM detects an excessively high IAT signal voltage, indicating a low temperature, DTC P0113 sets.

1. DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0125, P0128, P0502, P0503 are not set.
2. The engine run time is more than 120 seconds.
3. The vehicle speed sensor (VSS) indicates that the vehicle speed is less than 11 km/h (7 mph).
4. The engine coolant temperature (ECT) is more than 60°C (140°F).
5. The mass air flow (MAF) is less than 15 g/s.

The PCM detects that the IAT Sensor parameter is less than -38°C (-36°F) for more than 5 seconds.

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

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

1. When the vehicle is at ambient temperature the IAT sensor and the ECT sensor temperatures should be relatively close to each other. Refer to «Temperature vs Resistance»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-57l-introduction__temperature-vs-resistance) .
2. If a short to a separate 5-volt source occurs this DTC may set.
3. If an intermittent condition is suspected, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-57l-troubleshooting__intermittent-conditions) .

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

1. 6: This step tests for the proper operation of the circuit in the low voltage range.

DTC P0113

The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The powertrain control module (PCM) supplies 5 volts to the signal circuit and a ground for the ECT low reference circuit. When the ECT is low, the sensor resistance is high. When the ECT is high, the sensor resistance is low. The PCM uses this input for engine controls and enabling criteria for diagnostics. The PCM uses this High Side Coolant Rationality test to determine if the ECT input is skewed high. The internal clock of the PCM will record the amount of time the ignition is OFF. At restart the PCM will compare the temperature difference between the ECT and the intake air temperature (IAT). This DTC will only run once during the ignition cycle within the enabling conditions. Before failing this test, the PCM will perform a calculation to determine the presence of a block heater. If the PCM detects that the temperature difference is not within the calibrated range after the ignition OFF time, DTC P0116 sets.

1. The ignition is ON.
2. DTCs P0112, P0113, P0117, P0118, P0125, P0128, P0601, P0602, P1621, P2610 are not set.
3. The vehicle has a minimum ignition off time of 10 hours.
4. The IAT sensor parameter is more than 15°C (59°F).

If the PCM detects a temperature difference between the ECT sensor and the IAT sensor of more than 15°C (27°F), the vehicle must be driven for more than 400 seconds over 24 km/h (15 mph). If the IAT sensor temperature decreases more than 3°C (5°F), a block heater is detected and the test is aborted. If the IAT sensor temperature does not decrease, a block heater was not detected and DTC P0116 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.

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. 7: A snapshot is the quickest method to capture the data before it changes.
2. 8: An IAT sensor that is skewed low can cause this DTC to set.
3. 10: This step will determine if high resistance has caused this DTC to set.
4. 12: A high resistance short from the signal circuit to the low reference circuit can cause this DTC to set.

DTC P0116

The engine coolant temperature (ECT) sensor is a variable resistor, that measures the temperature of the engine coolant. The powertrain control module (PCM) supplies 5 volts to the ECT signal circuit and a ground for the ECT low reference circuit. When the ECT is cold, the sensor resistance is high. When the ECT increases, the sensor resistance decreases. With high sensor resistance, the PCM detects a high voltage on the ECT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the ECT signal circuit. If the PCM detects an excessively low ECT signal voltage, which is a high temperature indication, DTC P0117 sets.

The engine run time is more than 10 seconds.

OR

The engine run time is less than 10 seconds when IAT is less than 50°C (122°F).

The ECT sensor temperature is more than 139°C (282°F) for more than 20 seconds.

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

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

1. An overheating condition may cause this DTC to set.
2. After starting the engine, the ECT should rise steadily to about 90°C (194°F) then stabilize when the thermostat opens.
3. Use the Temperature vs. Resistance table to test the ECT sensor at various temperature levels to evaluate the possibility of a skewed sensor. A skewed sensor could result in poor driveability concerns. Refer to «Temperature vs Resistance»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-57l-introduction__temperature-vs-resistance) .
4. If the condition is suspected of being intermittent, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-57l-troubleshooting__intermittent-conditions) .

DTC P0117

The engine coolant temperature (ECT) sensor is a variable resistor, that measures the temperature of the engine coolant. The ECT sensor has a signal circuit and a low reference circuit. The powertrain control module (PCM) supplies 5 volts to the ECT signal circuit and a ground for the ECT low reference circuit. When the ECT is cold, the sensor resistance is high. When the ECT increases, the sensor resistance decreases. With high sensor resistance, the PCM detects a high voltage on the ECT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the ECT signal circuit. If the PCM detects an excessively high ECT signal voltage, which is a low temperature indication, DTC P0118 sets.

The engine has been running for more than 60 seconds.

OR

The engine run time is less than 60 seconds when the intake air temperature (IAT) is more than 0°C (32°F)

The PCM detects that the ECT sensor parameter is less than -38°C (-36°F) for 20 seconds.

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

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

1. If a short to a separate 5-volt source occurs, this DTC may set.
2. After starting the engine, the ECT should rise steadily, then stabilize when the thermostat opens.
3. Use the Temperature vs. Resistance table to test the ECT sensor. A skewed sensor could result in poor driveability conditions. Refer to «Temperature vs Resistance»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-57l-introduction__temperature-vs-resistance) .
4. If the condition is suspected of being intermittent, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-57l-troubleshooting__intermittent-conditions) .

DTC P0118

The throttle position (TP) sensor is mounted on the throttle body assembly. The sensor is actually 2 individual TP sensors within 1 housing. Two separate signal circuits, low reference circuits and 5-volt reference circuits are used in order to connect the TP sensor assembly to the throttle actuator control (TAC) module. The 2 sensors have opposite functionality. The TP sensor 1 signal voltage is pulled up to the reference voltage as the throttle opens, from below 1 volt at closed throttle to above 3.5 volts at wide open throttle (WOT). The TP sensor 2 signal voltage is pulled down to low reference from around 3.8 volts at closed throttle to below 1 volt at WOT. TP sensor 1 and accelerator pedal position (APP) sensor 1 share a 5-volt reference circuit that is connected within the TAC module. TP sensor 2 and APP sensor 2 share a 5-volt reference circuit that is connected within the TAC module. If an out of range condition is detected with the TP sensor 1, this DTC will set and the Reduced Engine Power message will be displayed.

1. DTCs P2108, or P1518 are not set.
2. The ignition switch is in the crank or in the run position.
3. The ignition voltage greater than 5.23 volts.

1. TP sensor 1 signal voltage is less than 0.13 volts or greater than 4.87 volts.
2. All of the above conditions present for less 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 and/or the Failure Records.
3. The control module commands the TAC system to operate in the Reduced Engine Power mode.
4. A message center or an indicator displays Reduced Engine Power.
5. Under certain conditions the control module commands the engine OFF.

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 TAC module connectors for signs of water intrusion. When water intrusion occurs, multiple DTCs could be set with no DTC circuit or component conditions found during diagnostic testing.
2. When the TAC module detects a condition within the TAC system, more than one TAC system related DTC may set. This is due to the many redundant tests that run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting the components during testing may set additional DTCs. Keep this in mind when reviewing the Capture info.
3. If this DTC is determined to be intermittent, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-57l-troubleshooting__intermittent-conditions) .

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

1. 33: When the TAC module detects a condition within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests that run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting the components during testing may set additional DTCs. Keep this in mind when reviewing the Capture Info.

DTC P0120

The engine coolant temperature (ECT) sensor monitors the temperature of the coolant. This input is used by the powertrain control module (PCM) for engine control, and as an enabling criteria for some diagnostics.

The air flow coming into the engine is accumulated and used to determine if the vehicle has been driven within the conditions that would allow the engine coolant to heat up normally to the Closed Loop temperature. If the coolant temperature does not increase normally or does not reach Closed Loop temperature, the diagnostics that use engine coolant temperature as enabling criteria may not run when expected.

This DTC will only run once per ignition cycle within the enabling conditions. If the PCM detects the calibrated amount of air flow and engine run time have been met and the ECT has not met the Closed Loop temperature, DTC P0125 sets.

1. DTCs P0101, P0102, P0103, P0112, P0113, P0116, P0117, P0118, P0500, P0502, P0503 are not present.
2. The intake air temperature (IAT) sensor parameter is between -7 to +55°C (+19 to +131°F).
3. The start-up engine coolant temperature parameter is less than 28.5°C (83°F).
4. The engine is running between 120-1,370 seconds.
5. The vehicle speed is more than 8 km/h (5 mph) for more than 0.8 km (0.5 miles).
6. The mass air flow (MAF) is between 15-75 g/s with the average more than 14 g/s.

1. The calibrated amount of engine run time has been met.
2. The calibrated amount of engine air flow has been met.
3. The calibrated vehicle speed and distance have been met.
4. The engine coolant temperature for Closed Loop of 34°C (93°F) has not been met.

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

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

DTC P0125

An engine coolant temperature (ECT) sensor monitors the temperature of the coolant. This input is used by the powertrain control module (PCM) for engine control, and as an enabling criteria for some diagnostics.

The air flow coming into the engine is accumulated and used to determine if the vehicle has been driven within the conditions that would allow the engine coolant to heat up normally to the thermostat regulating temperature. If the coolant temperature does not increase normally or does not reach the regulating temperature of the thermostat, diagnostics that use ECT as enabling criteria, may not run when expected. This DTC will only run once per ignition cycle within the enabling conditions.

If the PCM detects the calibrated amount of air flow and engine run time have been met and the ECT has not met the minimum thermostat regulating temperature, DTC P0128 sets.

1. DTCs P0101, P0102, P0103, P0112, P0113, P0116, P0117, P0118, P0125, P0500, P0502, P0503 are not present.
2. The start up engine coolant temperature is less than 70°C (158°F).
3. The intake air temperature (IAT) sensor parameter is between -7 to +55°C (+19 to +131°F).
4. The engine is running between 120-1,370 seconds.
5. The vehicle speed is more than 8 km/h (5 mph) for more than 2.5 kilometers (1.5 miles).
6. The mass air flow (MAF) is between 15-75 g/s with the average more than 14 g/s.

1. The calibrated amount of engine run time has been met.
2. The calibrated amount of engine air flow has been met.
3. The calibrated vehicle speed and distance have been met.
4. The calibrated minimum engine coolant temperature of 75°C (167°F) has not been met.

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

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

DTC P0128

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and closed loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream. If the PCM detects an HO2S voltage that stays below a specified value, DTC P0131 sets for HO2S bank 1 sensor 1, or DTC P0151 sets for HO2S bank 2 sensor 1.

Lean Test Enable

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
2. The Loop Status parameter is closed.
3. The Ignition 1 Signal parameter is between 10-18 volts.
4. The Fuel Tank Level Remaining parameter is more than 10 percent.
5. The TP Indicated Angle parameter is between 3-70 percent more than the value observed at idle.

OR

Power Enrichment Test Enable

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
2. The Loop Status parameter is closed.
3. The Ignition 1 Signal parameter is between 10-18 volts.
4. The Fuel Tank Level Remaining parameter is more than 10 percent.
5. The Engine Run Time parameter is more than 30 seconds.
6. The Power Enrichment parameter is active for more than 1 second.

Lean Test

The PCM detects that the affected HO2S voltage parameter is less than 200 mV for 165 seconds.

OR

Power Enrichment Test

The PCM detects that the affected HO2S voltage parameter is less than 360 mV for 10 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.
3. The control module commands the Loop Status open.

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

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

1. 2: If the voltage is varying above and below the specified range, the condition is not present.

DTC P0131 or P0151

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and closed loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream. If the PCM detects an HO2S voltage that stays above a specified value, DTC P0132 sets for HO2S bank 1 sensor 1, or DTC P0152 sets for HO2S bank 2 sensor 1.

Rich Test Enable

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
2. The Loop Status parameter is closed.
3. The Ignition 1 Signal parameter is between 10-18 volts.
4. The Fuel Tank Level Remaining parameter is more than 10 percent.
5. The TP Indicated Angle parameter is between 3-70 percent more than the value observed at idle.

OR

Decel Fuel Cutoff Test Enable

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
2. The Loop Status parameter is closed.
3. The Ignition 1 Signal parameter is between 10-18 volts.
4. The Fuel Tank Level Remaining parameter is more than 10 percent.
5. The Engine Run Time parameter is more than 30 seconds.
6. The Decel. Fuel Cutoff parameter is active for more than 2 seconds.

Rich Test

The PCM detects that the affected HO2S voltage parameter is more than 900 mV for 165 seconds.

OR

Decel Fuel Cutoff Test

The PCM detects that the affected HO2S voltage parameter is more than 540 mV for 5 seconds.

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

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

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

1. 2: If the voltage is varying above and below the specified range, the condition is not present.

DTC P0132 or P0152

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and closed loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream. This diagnostic will only run once per ignition cycle. The PCM monitors the rich-to-lean and lean-to-rich transition time. A transition is defined as, the HO2S voltage changes from above 625 mV to below 250 mV or from below 250 mV to above 625 mV. If the PCM detects that the transition time is too long, DTC P0133 sets for HO2S bank 1 sensor 1, or DTC P0153 sets for HO2S bank 2 sensor 1.

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0131, P0132, P0134, P0135, P0151, P0152, P0154, P0155, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
2. The ECT Sensor parameter is more than 50°C (122°F).
3. The EVAP Purge Solenoid Command parameter is more than 1 percent.
4. The MAF Sensor parameter is between 20-55 g/s.
5. The Engine Speed parameter is between 1,000-2,300 RPM.
6. The TP Indicated Angle parameter is 5 percent more than the value observed at idle.
7. The Loop Status parameter is closed.
8. The Ignition 1 Signal parameter is between 10-18 volts.
9. The Fuel Tank Level Remaining parameter is more than 10 percent.
10. The Engine Run Time parameter is more than 160 seconds.
11. The above conditions are met for 60 seconds.

The PCM detects that the affected HO2S rich-to-lean or lean-to-rich average response time is more than a calibrated 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.

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

1. 2: If the voltage is varying above and below the specified value, the condition is not present.

DTC P0133 or P0153

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and closed loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream. If the PCM detects that the HO2S voltage remains within the bias voltage range, DTC P0134 sets for HO2S bank 1 sensor 1, or DTC P0154 sets for HO2S bank 2 sensor 1.

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
2. The Engine Run Time parameter is more than 300 seconds.
3. The Ignition 1 Signal parameter is between 10-18 volts.

The PCM detects that the affected HO2S voltage parameter is between 350-550 mV for 60 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.
3. The control module commands the Loop Status open.

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. 3: If the voltage is varying above and below the specified value, the condition is not present.

DTC P0134 or P0154

The heated oxygen sensor (HO2S) must reach operating temperature to provide an accurate voltage signal. A heating element inside the HO2S minimizes the time required for the sensor to reach operating temperature. Voltage is provided to the heater by the ignition 3 voltage circuit through a fuse. With the engine running, ground is provided to the heater by the HO2S heater low control circuit, through a low side driver within the powertrain control module (PCM). The PCM commands the heater ON or OFF to maintain a specific HO2S operating temperature range. The PCM determines the temperature by measuring the current flow through the heater. When the heater is in the ON state, the PCM will pulse the heater OFF for a duration of 50 ms, once per second. When the heater is in the OFF state, the PCM will pulse the heater ON for a duration of 50 ms, once per second. The PCM monitors the heater current with the engine running. The PCM also calculates the heater resistance on a cold start. Both diagnostics will only run once per ignition cycle. If the PCM detects that the heater current or the heater calculated resistance is not within the expected range, the following DTCs will set

1. DTC P0135 for HO2S bank 1 sensor 1
2. DTC P0141 for HO2S bank 1 sensor 2
3. DTC P0155 for HO2S bank 2 sensor 1
4. DTC P0161 for HO2S bank 2 sensor 2

Heater Current Test

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
2. The ECT Sensor parameter is more than 50°C (122°F).
3. The Ignition 1 Signal parameter is between 10-18 volts.
4. The MAF Sensor parameter is between 3-40 g/s.
5. The Engine Speed parameter is between 500-3,000 RPM.
6. The Engine Run Time parameter is more than 120 seconds.

Heater Resistance Test

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1258 are not set.
2. The ignition is OFF for more than 10 hours.
3. The ECT Sensor parameter is between -30 and +45°C (-22 and +113°F) at engine start-up.
4. The ECT Sensor parameter minus the IAT Sensor parameter is less than 8°C (14°F) at engine start-up.
5. The engine is started.

Heater Current Test

1. DTCs P0135 or P0155 The PCM detects that the affected HO2S Heater Current parameter is more than 3.125 amps or less than 0.25 amps. The above condition is met for 10 seconds.
2. DTCs P0141 or P0161 The PCM detects that the affected HO2S Heater Current parameter is more than 1.375 amps or less than 0.25 amps. The above condition is met for 10 seconds.

Heater Resistance Test

DTCs P0135, P0141, P0155, or P0161-The PCM detects that the affected HO2S heater calculated resistance is not within an expected range at engine start-up.

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

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

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

1. 11: With no fault present, the test lamp will blink once per second.

DTC P0135, P0141, P0155, or P0161

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and closed loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream.

The HO2S bank 1 sensor 2 and HO2S bank 2 sensor 2 are used for catalyst monitoring. This diagnostic runs once per ignition cycle. This diagnostic consists of two tests, a passive test and an intrusive test. During the passive test, if the HO2S bank 1 sensor 2 or HO2S bank 2 sensor 2 voltage transitions below 350 mV and above 709 mV, the DTC will pass for this ignition cycle. If the DTC does not pass during the passive test, the intrusive test will begin. During the intrusive test, the control module will force the air-to-fuel ratio rich and/or lean. The control module then waits for a predicted response from the HO2S. If the HO2S voltage transitions below 350 mV and/or above 709 mV, the DTC will pass for this ignition cycle. If the control module does not receive the expected response from the HO2S, DTC P0136 will set for HO2S bank 1 sensor 2 or DTC P0156 will set for HO2S bank 2 sensor 2.

DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0157, P0158, P0160, P0161, P0200, P0442, P0443, P0446, P0449, P0455, P0496, P1133, P1134, P1153, P1154 are not set.

Passive Test

1. The engine is running.
2. The Engine Run Time parameter is less than 13.5 minutes.

Intrusive Test

1. The Engine Run Time parameter is more than 13.5 minutes.
2. The ignition 1 Signal parameter is between 10-18 volts.
3. The Engine Speed parameter is between 500-5,000 RPM.
4. The MAF Sensor parameter is between 5-55 g/s.
5. The Vehicle Speed parameter is between 24-131 km/h (15-82 mph).
6. The Short Term FT Bank 1 and Bank 2 parameter is between -10 and +10 percent.
7. The maximum number of intrusive attempts is less than 13.

1. The PCM detects that the HO2S bank 1 sensor 2 or HO2S bank 2 sensor 2 did not transition below 350 mV and above 709 mV during the passive test.
2. One of the following tests fail: Lean Intrusive Test The PCM detects that the HO2S bank 1 sensor 2 or HO2S bank 2 sensor 2 is more than 350 mV for 25.4 seconds. The HO2S bank 1 sensor 1 and HO2S bank 2 sensor 1 is less than 300 mV. OR Rich Intrusive Test The PCM detects that the HO2S bank 1 sensor 2 or HO2S bank 2 sensor 2 is less than 709 mV for 25.4 seconds. The HO2S bank 1 sensor 1 and HO2S bank 2 sensor 1 is more than 600 mV.

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

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

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

1. 2: If the voltage does not change more that the specified value, the condition is present.

DTC P0136 or P0156

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and closed loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream. If the PCM detects an HO2S voltage that stays below a specified value, DTC P0137 sets for HO2S bank 1 sensor 2, or DTC P0157 sets for HO2S bank 2 sensor 2.

Lean Test Enable

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
2. The Loop Status parameter is closed.
3. The Ignition 1 Signal parameter is between 10-18 volts.
4. The Fuel Tank Level Remaining parameter is more than 10 percent.
5. The TP Indicated Angle parameter is between 3-70 percent more than the value observed at idle.

OR

Power Enrichment Test Enable

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
2. The Loop Status parameter is closed.
3. The Ignition 1 Signal parameter is between 10-18 volts.
4. The Fuel Tank Level Remaining parameter is more than 10 percent.
5. The Engine Run Time parameter is more than 30 seconds.
6. The Power Enrichment parameter is active for more than 2 seconds.

The PCM detects that the affected HO2S voltage parameter is less than 80 mV for 200 seconds.

OR

The PCM detects that the affected HO2S voltage parameter is less than 420 mV for 10 seconds.

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

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

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

1. 2: If the voltage does not change more that the specified value, the condition is present.

DTC P0137 or P0157

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and closed loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream. If the PCM detects an HO2S voltage that stays above a specified value, DTC P0138 sets for HO2S bank 1 sensor 2, or DTC P0158 sets for HO2S bank 2 sensor 2.

Rich Test Enable

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
2. The Loop Status parameter is closed.
3. The Ignition 1 Signal parameter is between 10-18 volts.
4. The Fuel Tank Level Remaining parameter is more than 10 percent.
5. The TP Indicated Angle parameter is between 3-70 percent more than the value observed at idle.

OR

Decel. Fuel Cutoff Test Enable

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
2. The Loop Status parameter is closed.
3. The Ignition 1 Signal parameter is between 10-18 volts.
4. The Fuel Tank Level Remaining parameter is more than 10 percent.
5. The Engine Run Time parameter is more than 30 seconds.
6. The Decel. Fuel Cutoff parameter is active for more than 10 seconds.

The PCM detects that the affected HO2S voltage parameter is more than 950 mV for 200 seconds.

OR

The PCM detects that the affected HO2S voltage parameter is more than 480 mV for 5 seconds.

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

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

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

1. 2: If the voltage does not change more that the specified value, the condition is present.

DTC P0138 or P0158

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and closed loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream. This diagnostic will only run once per ignition cycle. If the PCM detects that the HO2S voltage remains within the bias voltage range, DTC P0140 sets for HO2S bank 1 sensor 2, or P0160 sets for HO2S bank 2 sensor 2.

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0141, P0161, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
2. The Engine Run Time parameter is more than 300 seconds.
3. The Loop Status is closed.
4. The Ignition 1 Signal parameter is between 10-18 volts.

1. The PCM detects that the affected HO2S voltage parameter is between 410-490 mV for 150 seconds.
2. The TP Indicated Angle parameter changes more than 5 percent within 1 second, 6 times.

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

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

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

1. 3: If the voltage is varying above and below the specified value, the condition is not present.

DTC P0140 or P0160

The powertrain control module (PCM) 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 PCM determines fuel delivery based on sensor signals without heated oxygen sensor (HO2S) input. During Closed Loop, the HO2S inputs are added and used by the PCM to calculate short and long term fuel trim fuel delivery adjustments. If the HO2S indicates a lean condition, fuel trim values will be above 0 percent. If the HO2S indicate a rich condition, fuel trim values will be below 0 percent. Short term fuel trim values change rapidly in response to the HO2S voltage signals. Long term fuel trim makes coarse adjustments in order to maintain an air/fuel ratio of 14.7:1. If the PCM detects an excessively lean condition, DTC P0171 or P0174 sets.

1. DTCs P0101, P0103, P0108, P0135, P0137, P0141, P0200, P0300, P0420, P0430, P0442, P0443, P0446, P0449, P0506, or P0507 are not set.
2. The engine coolant temperature (ECT) is between 75-115°C (167-239°F).
3. The intake air temperature (IAT) is between -20 and +90°C (4-194°F).
4. The manifold absolute pressure (MAP) is between 26-90 kPa (3.8-13 psi).
5. The vehicle speed is less than 137 km/h (85 mph).
6. The engine speed is between 400-3,000 RPM.
7. The barometric pressure (BARO) is more than 74 kPa (10.7 psi).
8. The mass airflow (MAF) is between 5-90 g/s.
9. The fuel level is more than 10 percent.
10. The throttle position (TP) is less than 90 percent.

1. The average long term fuel trim cell value is above 23 percent.
2. All of the above conditions are present for 6 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. The system may become lean if an injector is not suppling enough fuel.
2. A lean condition could be present during high fuel demand.
3. Use a scan tool in order to review the Failure Records. If an intermittent condition is suspected, refer to «Intermittent Conditions»(/cadillac/cts/i-2002-2007/remont/testing-diagnostics/#engine-controls-57l-troubleshooting__intermittent-conditions) .

DTC P0171 or P0174

See also:
• Intermittent Conditions
• Engine Controls Schematics
• Powertrain Control Module (PCM) Connector End Views
• Engine Controls Connector End Views
• Diagnostic System Check - Engine Controls
• Diagnostic Trouble Code (DTC) List
• Altitude vs Barometric Pressure
• Restricted Exhaust
• Circuit Testing
• Measuring Voltage Drop
• Testing for Intermittent Conditions and Poor Connections
• Connector Repairs
• Wiring Repairs
• Probing Electrical Connectors
• Testing for Short to Ground
• Checking Aftermarket Accessories
• Timing Chain and Sprockets Replacement
• Engine Compression Test
• DTC P0641
• Using Connector Test Adapters
• Temperature vs Resistance
• Using Fused Jumper Wires
• Draining and Filling Cooling System (LA3, LY9)
• Scan Tool Snapshot Procedure
• Accelerator Pedal Position (APP) Sensor Replacement
• Thermostat Diagnosis (LY7)
• Thermostat Diagnosis (LS6)
• Scan Tool Data List
• Silicon Contamination of Heated Oxygen Sensors Notice
• Fuel System Diagnosis
• Oil Consumption Diagnosis
• Loss of Coolant (M 35)
• Loss of Coolant (M 82)
• Crankcase Ventilation System Inspection/Diagnosis
• DTC P0106