Engine Controls - 2.0l (DTC p0132 to p0340) Chevrolet Cobalt I

Circuit Description

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.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC P0132 HO2S Circuit High Voltage Sensor 1

Conditions for Running the DTC

Rich Test Enable

1. DTCs P0068, P0069, P0097, P0098, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0201, P0202, P0203, P0204, P0220, P0442, P0443, P0446, P0449, P0452, P0453, P0461, P0496, P1516, P1681, P2101, P2135, P2176 are not set.
2. The Loop Status parameter is closed.
3. The Ignition 1 Signal parameter is between 11-18 volts.
4. The Fuel Level Sensor parameter is more than 10 percent.
5. The Throttle Position (TP) Sensor parameter is between 0-50 percent.
6. The catalyst test is not active.
7. Traction control is not active.
8. The air/fuel ration is between 14.5-14.8.
9. DTC P0132 runs the rich test continuously when the above conditions are met for 2 seconds.

Decel Fuel Cutoff Test Enable

1. DTCs P0068, P0069, P0097, P0098, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0201, P0202, P0203, P0204, P0220, P0442, P0443, P0446, P0449, P0452, P0453, P0461, P0496, P1516, P1681, P2101, P2135, P2176 are not set.
2. The Ignition 1 Signal parameter is between 11-18 volts.
3. The Fuel Level Sensor parameter is more than 10 percent.
4. The Engine Run Time parameter is more than 200 seconds.
5. The decel fuel cutoff mode is enabled.
6. The catalyst test is not active.
7. Traction control is not active.
8. DTC P0132 runs the decel fuel cutoff test continuously when the above conditions are met for 2 seconds.

Conditions for Setting the DTC

Rich Test

1. The PCM detects that the HO2S 1 parameter is more than 1,000 mV.
2. DTC P0132 sets within 15 seconds during the rich test when the above condition is met.

Decel Fuel Cutoff Test

1. The PCM detects that the HO2S 1 parameter is more than 900 mV.
2. DTC P0132 sets within 40 seconds during the decel fuel cutoff test when the above condition is met.

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.
3. The control module commands the Loop Status open.

Conditions for Clearing the MIL/DTC

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

DTC P0132

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 temperatures 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 650 mV to below 450 mV or from below 450 mV to above 650 mV. If the PCM detects that the transition time is too long, DTC P0133 will set.

This diagnostic procedure supports the following DTC

DTC P0133 HO2S Slow Response Sensor 1

1. DTCs P0030, P0068, P0069, P0097, P0098, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0125, P0128, P0131, P0132, P0134, P0201, P0202, P0203, P0204, P0220, P0300, P0442, P0443, P0446, P0449, P0452, P0453, P0461, P0496, P1133, P1516, P1681, P2101, P2135, or P2176 are not set.
2. The Engine Coolant Temperature (ECT) Sensor parameter is more than 70°C (158°F).
3. The Ignition 1 Signal parameter is between 11-18 volts.
4. The Fuel Level Sensor parameter is more than 10 percent.
5. The Engine Run Time parameter is more than 200 seconds.
6. The Engine Speed parameter is between 1,000-3,500 RPM.
7. The Manifold Absolute Pressure (MAP) Sensor parameter is more than 30 kPa.
8. The Mass Airflow (MAF) Sensor parameter is between 15-50 g/s.
9. The Loop Status parameter is closed.
10. The Throttle Position (TP) Indicated Angle parameter is more than 5 percent.
11. The catalyst test is not active.
12. Traction control is not active.
13. No fuel injectors are disabled.
14. The transmission is not in Park, Reverse, or Neutral.
15. DTC P0133 runs once per drive cycle when the above conditions are met for 2 seconds.

1. The PCM detects that the HO2S 1 rich-to-lean or lean-to-rich average response time is more than 0.1 second.
2. DTC P0133 sets within 60 seconds when the above condition is 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.

Test Description

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

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 temperatures 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 will set.

This diagnostic procedure supports the following DTC

DTC P0134 HO2S Circuit Insufficient Activity Sensor 1

1. DTCs P0068, P0069, P0097, P0098, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0125, P0128, P0201, P0202, P0203, P0204, P0220, P0442, P0443, P0446, P0449, P0452, P0453, P0461, P0496, P1516, P1681, P2101, P2135, P2176 are not set.
2. The Engine Coolant Temperature (ECT) Sensor parameter is more than 70°C (158°F).
3. The Ignition 1 Signal parameter is between 11-18 volts.
4. The catalyst diagnostic test is not active.
5. Traction control is not active.
6. The engine run time is more than 200 seconds.
7. DTC P0134 runs continuously when the above conditions are met.

1. The PCM detects that the HO2S 1 parameter is between 400-500 mV.
2. The Throttle Position (TP) Indicated Angle parameter changes more than 1 percent, 3 times.
3. DTC P0134 sets within 100 seconds when the above conditions are met.

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

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

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

1. 2: An HO2S heater fault may set this DTC.
2. 3: If the voltage is varying above and below the specified value, the condition is not present.

DTC P0134

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. 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 1 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 and calculating the resistance. Based on the resistance the PCM can predict the sensor temperature. For diagnosis 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 an expected range, DTC P0135 sets.

This diagnostic procedure supports the following DTC

DTC P0135 HO2S Heater Performance Sensor 1

Heater Current Test

1. DTCs P0030 is not set.
2. The Ignition 1 Signal parameter is between 11-18 volts.
3. The Mass Airflow (MAF) Sensor parameter is between 5-25 g/s.
4. The Engine Run Time parameter is more than 60 seconds.
5. The Engine Speed parameter is between 500-3,000 RPM.
6. The Ignition 1 Signal parameter varies less than 1 volt.
7. DTC P0135 runs the heater current test twice per drive cycle when the above conditions are met for 2 seconds.

Heater Resistance Test

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0201, P0202, P0203, P0204, P0442, P0443, P0446, P0449, P0452, P0453, P0455, P0496, P1516, P2101, P2135, P2176 are not set.
2. The ignition is OFF for more than 10 hours.
3. The ECT Sensor parameter is between -30°C and +45°C (-22°F and +113°F) at engine start-up.
4. The ECT Sensor parameter minus the Intake Air Temperature (IAT) Sensor parameter is less than 140°C (252°F) at engine start-up.
5. The engine is started.
6. DTC P0135 runs the heater resistance test once per drive cycle when the above conditions are met.

Heater Current Test

1. The PCM detects that the HO2S 1 Heater Current parameter is more than 1.7 amps or less than 0.301 amps.
2. DTC P0135 sets during the heater current test within 60 seconds when the above condition is met.

Heater Resistance Test

1. The PCM detects that the HO2S 1 heater calculated resistance is not within the expected range at engine start-up.
2. DTC P0135 sets during the heater resistance test within 5 seconds when the above condition is 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 P0135

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 2 is used for catalyst monitoring. This diagnostic runs once per ignition cycle. This diagnostic consists of 2 tests, a passive test and an intrusive test. During the passive test, if the HO2S 2 voltage transitions below 300 mV and above 700 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 both sensors. If the HO2S 2 voltage transitions below 300 mV and/or above 700 mV, the DTC will pass for this ignition cycle. If the control module does not receive the expected response from the HO2S 2, DTC P0136 will set.

This diagnostic procedure supports the following DTC

DTC P0136 HO2S Circuit Malfunction Sensor 2

DTCs P0030, P0036, P0068, P0069, P0097, P0098, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0125, P0128, P0130, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0171, P0172, P0201, P0202, P0203, P0204, P0220, P0442, P0443, P0446, P0449, P0452, P0453, P0461, P0496, P1133, P1516, P1681, P2101, P2135, or P2176 are not set.

Passive Test

1. The engine is running.
2. The Engine Run Time parameter is less than 13.3 minutes.
3. DTC P0136 runs the passive test once per drive cycle when the above conditions have been met for 2 seconds.

Intrusive Test

1. The Engine Run Time parameter is more than 13.3 minutes.
2. The ignition 1 Signal parameter is between 11-18 volts.
3. The Mass Airflow (MAF) Sensor parameter is between 14-100 g/s.
4. The Engine Speed parameter is between 1,000-5,000 RPM.
5. The Vehicle Speed parameter is between 30-130 km/h (19-81 mph).
6. The Short Term FT parameter is between -20 and +20 percent.
7. The maximum number of intrusive attempts is less than 50.
8. The passive test did not pass.
9. DTC P0136 runs the intrusive test once per drive cycle when the above conditions are met.

1. The PCM detects that the HO2S 2 did not transition below 300 mV and above 700 mV during the passive test.
2. One of the following tests fail: Lean Intrusive Test The PCM detects that the HO2S 2 is more than 300 mV. The HO2S 1 is less than 300 mV. DTC P0136 sets during the lean intrusive test within 30 seconds when the above condition is met. OR Rich Intrusive Test The PCM detects that the HO2S 2 is less than 700 mV. The HO2S 1 is more than 600 mV. DTC P0136 sets during the rich intrusive test within 30 seconds when the above condition is 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.

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

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

DTC P0136

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 2 voltage that stays below a specified value, DTC P0137 will set.

This diagnostic procedure supports the following DTC

DTC P0137 HO2S Circuit Low Voltage Sensor 2

Lean Test Enable

1. DTCs P0068, P0069, P0097, P0098, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0201, P0202, P0203, P0204, P0220, P0442, P0443, P0446, P0449, P0452, P0453, P0461, P0496, P1516, P1681, P2101, P2135, P2176 are not set.
2. The Loop Status parameter is closed.
3. The Ignition 1 Signal parameter is between 11-18 volts.
4. The Fuel Level Sensor parameter is more than 10 percent.
5. The Throttle Position (TP) Sensor parameter is between 15-50 percent.
6. The catalyst diagnostic is not active.
7. Traction control is not active.
8. The air/fuel ratio is between 14.5-14.8.
9. DTC P0137 runs the lean test continuously when the above conditions have been met for 2 seconds.

Power Enrichment Test Enable

1. DTCs P0068, P0069, P0097, P0098, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0201, P0202, P0203, P0204, P0220, P0442, P0443, P0446, P0449, P0452, P0453, P0461, P0496, P1516, P1681, P2101, P2135, P2176 are not set.
2. The Loop Status parameter is closed.
3. The Ignition 1 Signal parameter is between 11-18 volts.
4. The Fuel Level Sensor parameter is more than 10 percent.
5. The Engine Run Time parameter is more than 200 seconds.
6. The power enrichment mode is enabled.
7. The catalyst diagnostic is not active.
8. Traction control is not active.
9. DTC P0137 runs the power enrichment test continuously when the above conditions have been met for 2 seconds.

Lean Test

1. The PCM detects that the HO2S 2 Voltage parameter is less than 50 mV for 100 seconds.
2. DTC P0137 sets within 100 seconds during the lean test when the above condition is met.

Power Enrichment Test

1. The PCM detects that the HO2S 2 Voltage parameter is less than 700 mV for 100 seconds.
2. DTC P0137 sets within 100 seconds during the power enrichment test when the above condition is 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.

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

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

DTC P0137

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 2 voltage that stays above a specified value, DTC P0138 will set.

This diagnostic procedure supports the following DTC

DTC P0138 HO2S Circuit High Voltage Sensor 2

Rich Test Enable

1. DTCs P0068, P0069, P0097, P0098, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0201, P0202, P0203, P0204, P0220, P0442, P0443, P0446, P0449, P0452, P0453, P0461, P0496, P1516, P1681, P2101, P2135, or P2176 are not set.
2. The Loop Status parameter is closed.
3. The Ignition 1 Signal parameter is between 11-18 volts.
4. The Fuel Level Sensor parameter is more than 10 percent.
5. The Throttle Position (TP) Sensor parameter is between 15-50 percent.
6. The catalyst diagnostic is not active.
7. Traction control is not active.
8. The air/fuel ratio is between 14.5-14.8.
9. DTC P0138 runs continuously during the rich test when the above conditions have been met for 2 seconds.

Decel Fuel Cutoff Test Enable

1. DTCs P0068, P0069, P0097, P0098, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0201, P0202, P0203, P0204, P0220, P0442, P0443, P0446, P0449, P0452, P0453, P0461, P0496, P1516, P1681, P2101, P2135, or P2176 are not set.
2. The Loop Status parameter is closed.
3. The Ignition 1 Signal parameter is between 11-18 volts.
4. The Fuel Level Sensor parameter is more than 10 percent.
5. The Engine Run Time parameter is more than 200 seconds.
6. The Decel Fuel Cutoff is active.
7. The catalyst diagnostic is not active.
8. Traction control is not active.
9. DTC P0138 runs continuously during the decel fuel cutoff test when the above conditions have been met for 2 seconds.

Rich Test

1. The PCM detects that the HO2S 2 parameter is more than 1,000 mV.
2. DTC P0138 sets within 100 seconds during the rich test when the above condition is met.

Decel Fuel Cutoff Test

1. The PCM detects that the HO2S 2 parameter is more than 900 mV.
2. DTC P0138 sets within 40 seconds during the decel fuel cutoff test when the above condition is 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.

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

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

DTC P0138

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 temperatures 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 2 voltage remains within the bias voltage range, DTC P0140 will set.

This diagnostic procedure supports the following DTC

DTC P0140 HO2S Circuit Insufficient Activity Sensor 2

1. DTCs P0036, P0068, P0069, P0097, P0098, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0141, P0201, P0202, P0203, P0204, P0220, P0442, P0443, P0446, P0449, P0452, P0453, P0461, P0496, P1516, P2101, P2135, or P2176 are not set.
2. The Engine Coolant Temperature (ECT) Sensor parameter is more than 70°C (158°F).
3. The Ignition 1 Signal parameter is between 11-18 volts.
4. The Engine Run Time parameter is more than 200 seconds.
5. The Loop Status parameter is closed.
6. The Throttle Position (TP) Indicated Angle parameter changes more than 1 percent at least 3 times.
7. The catalyst diagnostic is not active.
8. DTC P0140 runs once per drive cycle when the above conditions have been met.

1. The PCM detects that the HO2S 2 parameter is between 425-475 mV.
2. DTC P0140 sets within 100 seconds when the above conditions are met.

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

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

DTC P0140

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. 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 1 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 and calculating the resistance. Based on the resistance, the PCM can predict the sensor temperature. For diagnosis, 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 an expected range, DTC P0141 sets.

This diagnostic procedure supports the following DTC

DTC P0141 HO2S Heater Performance Sensor 2

Heater Current Test

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0201, P0202, P0203, P0204, P0442, P0443, P0446, P0449, P0452, P0453, P0496, P1516, P2101, P2135, or P2176 are not set.
2. The Engine Coolant Temperature (ECT) Sensor parameter is more than 70°C (158°F).
3. The Ignition 1 Signal parameter is between 11-18 volts.
4. The Mass Airflow (MAF) Sensor parameter is between 5-25 g/s.
5. The Engine Run Time parameter is more than 60 seconds.
6. The Engine Speed parameter is between 500-3,000 RPM.
7. The Ignition 1 Signal parameter varies less than 1 volt.
8. DTC P0141 runs the heater current test twice per drive cycle when the above conditions are met for 2 seconds.

Heater Resistance Test

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0201, P0202, P0203, P0204, P0442, P0443, P0446, P0449, P0452, P0453, P0496, P1516, P2101, P2135, or P2176 are not set.
2. The ignition is OFF for more than 10 hours.
3. The ECT Sensor parameter is between -30°C and +45°C (-22°F and +113°F) at engine start-up.
4. The ECT Sensor parameter minus the Intake Air Temperature (IAT) Sensor parameter is less than 140°C (252°F) at engine start-up.
5. The engine is started.
6. DTC P0141 runs the heater resistance test once per drive cycle when the above conditions are met.

Heater Current Test

1. The PCM detects that the HO2S 2 Heater Current parameter is more than 1.5 amps or less than 0.199 amps.
2. DTC P0141 sets within 115 seconds during the heater current test when the above condition is met.

Heater Resistance Test

1. The PCM detects that the HO2S 2 heater calculated resistance is not within an expected range at engine start-up.
2. DTC P0141 sets within 5 seconds during the heater resistance test when the above condition is 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 P0141

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 Loop 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 PCM adds HO2S inputs and level of purge to calculate the short and long term fuel trim adjustments. If the HO2S indicates a lean condition, the fuel trim values will be above 0 percent. If the HO2S indicates a rich condition, the fuel trim values will be below 0 percent. The short term fuel trim values change rapidly in response to the HO2S voltage signals. The long term fuel trim makes coarse adjustments in order to maintain an air/fuel ratio of 14.7:1. A block of cells contain information arranged in combinations of engine RPM and engine load for a full range of vehicle operating conditions. The long term fuel trim diagnostic is based on an average of cells currently being used. The PCM selects the cells based on the engine speed and load. If the PCM detects an excessively lean condition, DTC P0171 sets.

This diagnostic procedure supports the following DTC

DTC P0171 Fuel Trim System Lean

1. DTCs P0030, P0036, P0068, P0069, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0128, P0130, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0201-P0204, P0220, P0222, P0223, P0300, P0301-P0304, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496, P0506, P0507, P1133, P1134, P1516, P2101, P2119, P2120, P2125, P2135, P2138, P2176 are not set.
2. The engine is in Closed Loop status.
3. The engine coolant temperature (ECT) is between -7 and +120°C (+19.4 and +248°F).
4. The intake air temperature (IAT) is between -7 and +145°C (+19.4 and +293°F).
5. The manifold absolute pressure (MAP) is between 15-100 kPa (2.2-14.5 psi).
6. The vehicle speed is less than 132 km/h (82 mph).
7. The engine speed is between 400-6,100 RPM.
8. The mass air flow (MAF) is between 1-512 g/s.
9. The barometric pressure (BARO) is greater than 74 kPa (10.7 psi).
10. The fuel level is greater than 10 percent.
11. DTC P0171 runs continuously once the above conditions have been met.

1. The long term FT weighted average value is more than a calibrated value.
2. The above condition is present for more than 2 minutes.

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

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

Diagnostic Aids

1. Test for fuel contamination. Small amounts of water can be delivered to the fuel injectors and cause a lean exhaust indication. A lean exhaust indication can also be caused by too much alcohol in the fuel. Refer to «Alcohol/Contaminants-in-Fuel Diagnosis (w/o Special Tool)»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis) or «Alcohol/Contaminants-in-Fuel Diagnosis (w/ Special Tool)»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis) .
2. The system will go lean if an injector is not supplying enough fuel.
3. A lean condition could be present during high fuel demand due to a fuel pump that does not pump enough fuel, a plugged fuel filter, or a restricted fuel pipe.
4. Review the Failure Records with a scan tool. If an intermittent condition is suspected, refer to «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis__intermittent-conditions) .

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

1. 8: If conditions were not corrected, a worn cam, worn intake or exhaust valves, or other engine mechanical failure may be at fault.

DTC P0171

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 Loop 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 PCM adds HO2S inputs and level of purge to calculate the short and long term fuel trim adjustments. If the HO2S indicates a lean condition, the fuel trim values will be above 0 percent. If the HO2S indicates a rich condition, the fuel trim values will be below 0 percent. The short term fuel trim values change rapidly in response to the HO2S voltage signals. The long term fuel trim makes coarse adjustments in order to maintain Air/Fuel Ratio of 14.7:1. 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. A block of cells contain information arranged in combinations of engine RPM and engine load for a full range of vehicle operating conditions. The long term fuel trim diagnostic is based on an average of cells currently being used. The PCM selects the cells based on the engine speed and load. If the PCM detects an excessively rich condition, DTC P0172 sets.

This diagnostic procedure supports the following DTC

DTC P0172 Fuel Trim System Rich

1. DTCs P0030, P0036, P0068, P0069, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0128, P0130, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0201-P0204, P0220, P0222, P0223, P0300, P0301-P0304, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496, P0506, P0507, P1133, P1134, P1516, P2101, P2119, P2120, P2125, P2135, P2138, P2176 are not set.
2. The engine is in Closed Loop status.
3. The engine coolant temperature (ECT) is between -7 and +120°C (+19.4 and +248°F).
4. The intake air temperature (IAT) is between -7 and +145°C (+19.4 and +293°F).
5. The manifold absolute pressure (MAP) is between 15-100 kPa (2.2-14.5 psi).
6. The mass air flow (MAF) is between 1-512 g/s.
7. The vehicle speed is less than 132 km/h (82 mph).
8. The engine speed is between 400-6,100 RPM.
9. The barometric pressure (BARO) is greater than 74 kPa (10.7 psi).
10. The fuel level is more than 10 percent.
11. DTC P0172 runs continuously when the above conditions have been met.

1. The long term fuel trim weighted average value is less than a calibrated value.
2. The above condition is present for more than 2 minutes.

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 contamination, such as water and alcohol, will affect the fuel trim.
2. The system will go rich if the injectors are supplying too much fuel.
3. Using the scan tool, review the Failure Records. If an intermittent condition is suspected, refer to «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis__intermittent-conditions) .

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

1. 8: If conditions were not corrected, a worn cam, worn intake or exhaust valves or other engine mechanical failure may be at fault.

DTC P0172

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

DTC Descriptors

This diagnostic procedure supports the following DTCs

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

1. The engine is running.
2. The ignition voltage is more than 11 volts for 5 seconds.
3. DTC P0201-P0204 run continuously once the above conditions are met.

1. The control module detects an incorrect voltage on the fuel injector control circuit.
2. The above condition is met 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. Performing the Fuel Injector Coil Test may help isolate an intermittent condition. Refer to «Fuel Injector Coil Test»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis) .
2. For an intermittent condition, refer to «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis__intermittent-conditions) .

DTC P0201-P0204

The throttle position (TP) sensors 1 and 2 are located within the throttle body assembly. Each sensor has the following components

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

This provides the powertrain control module (PCM) with a signal voltage proportional to throttle plate movement. TP sensor 1 signal voltage at closed throttle is near the 5-volt reference and decreases as the throttle plate is opened. TP sensor 2 signal voltage at closed throttle is near the low reference and increases as the throttle plate is opened. When TP sensor 2 signal voltage is not within the predicted range, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0220 Throttle Position (TP) Sensor 2 Circuit

1. The ignition switch in the Unlock, Accessory, Crank, or Run position.
2. DTC P0641 is not set.
3. The ignition voltage is more than 5.23 volts.
4. DTC P0220 runs continuously when the above conditions are met.

The TP sensor 2 voltage is less than 0.28 volt or more than 4.7 volts for more than 0.4 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 PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic runs and passes.
2. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
3. The DTC can be cleared by using a scan tool.

DTC P0220

The throttle position (TP) sensor 1 and sensor 2 are located within the throttle body assembly. Each sensor has the following circuits

1. A 5-volt reference
2. A low reference
3. A signal

This provides the powertrain control module (PCM) with a signal voltage proportional to throttle plate movement. TP sensor 1 signal voltage at closed throttle is near the 5-volt reference and decreases as the throttle plate is opened. TP sensor 2 signal voltage at closed throttle is near the low reference and increases as the throttle plate is opened. If the PCM detects that the TP sensor 2 signal voltage is less than the predicted range, DTC P0222 sets.

This diagnostic procedure supports the following DTC

DTC P0222 Throttle Position (TP) Sensor 2 Circuit Low Voltage

1. The ignition switch is in the crank or run position.
2. DTC P0641 is not set.
3. The ignition voltage is more than 5.23 volts.
4. DTC P0222 runs continuously when the above conditions are met.

The PCM detects that the TP sensor 2 voltage is less than 0.28 volts for more than 0.4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame 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 PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic runs and passes.
2. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
3. The DTC can be cleared by using a scan tool.

DTC P0222

The throttle position (TP) sensor 1 and sensor 2 are located within the throttle body assembly. Each sensor has the following components

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

This provides the powertrain control module (PCM) with a signal voltage proportional to throttle plate movement. TP sensor 1 signal voltage at closed throttle is near the 5-volt reference and decreases as the throttle plate is opened. TP sensor 2 signal voltage at closed throttle is near the low reference and increases as the throttle plate is opened. If the PCM detects that the TP sensor 2 signal voltage is not within the predicted range, DTC P0223 sets.

This diagnostic procedure supports the following DTC

DTC P0223 Throttle Position (TP) Sensor 2 Circuit High Voltage

1. The ignition switch is in the Unlock, Accessory, Crank, or Run position.
2. DTC P0641 is not set.
3. The ignition voltage is more than 5.23 volts.
4. DTC P0223 runs continuously when the above conditions are met.

The PCM detects that the TP sensor 2 voltage is more than 4.7 volts for more than 0.4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame 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 PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic runs and passes.
2. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
3. The DTC can be cleared by using a scan tool.

DTC P0223

The control module enables the fuel pump relay when the ignition switch is turned ON. The control module will disable the fuel pump relay within 2 seconds unless the control module detects ignition reference pulses. The control module continues to enable the fuel pump relay as long as ignition reference pulses are detected. The control module disables the fuel pump relay within 2 seconds if ignition reference pulses cease to be detected and the ignition remains ON.

The control module monitors the voltage on the fuel pump relay control circuit. If the control module detects an incorrect voltage on the fuel pump relay control circuit, a fuel pump relay control DTC sets.

This diagnostic procedure supports the following DTC

DTC P0230 Fuel Pump Relay Control Circuit

1. The engine speed is more than 0 RPM.
2. The ignition voltage is between 11-18 volts.
3. DTC P0230 runs continuously once the above conditions are met.

1. The control module detects that the commanded state of the driver and the actual state of the control circuit do not match.
2. The above condition is met for a minimum of 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 P0230

System Description

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

This diagnostic procedure supports the following DTC

DTC P0300 Engine Misfire Detected

1. DTCs P0107, P0112, P0113, P0117, P0118, P0120, P0121, P0125, P0131, P0132, P0133, P0134, P0171, P0172, P0220, P0336, P0502, P0506, P0507, P0601, P1133, P1621, P2135 are not set.
2. The engine speed is between 469-6,400 RPM.
3. The ignition voltage is between 9-17 volts.
4. The engine coolant temperature (ECT) is between -7°C and +123°C (+20 and +254°F).
5. The engine has been running for more than 5 seconds.
6. The throttle position (TP) has not increased more than 8 percent in 1 second.
7. The TP has not decreased more than 1.5 percent in 1 second.
8. DTC P0300 runs continuously when the above conditions are met.

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

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

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

You must perform the CKP system variation learn procedure before proceeding with the diagnostic table. Refer to CKP System Variation Learn Procedure .

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

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

DTC P0300

The powertrain control module (PCM) uses information from the crankshaft position (CKP) sensor and the ignition control module (ICM) in order to determine when an engine misfire is occurring. By monitoring variations in the crankshaft rotation speed for each cylinder, the PCM is able to detect individual misfire events. A misfire rate that is high enough can cause the 3-way catalytic converter (TWC) to overheat under certain driving conditions. The malfunction indicator lamp (MIL) will flash ON and OFF when the conditions for TWC overheating are present. If the PCM detects a misfire rate for a specific cylinder sufficient to cause emission levels to exceed mandated standards, DTC P0301, P0302, P0303, or P0304 will set.

This diagnostic procedure supports the following DTCs

1. DTC P0301 Cylinder 1 Misfire Detected
2. DTC P0302 Cylinder 2 Misfire Detected
3. DTC P0303 Cylinder 3 Misfire Detected
4. DTC P0304 Cylinder 4 Misfire Detected

1. DTCs P0105, P0107, P0112, P0113, P0117, P0118, P0120, P0121, P0125, P0131, P0132, P0133, P0134, P0171, P0172, P0220, P0335, P0502, P0506, P0507, P0601, P1133, P1621, P2135 are not set.
2. The engine speed is between 469-6,400 RPM.
3. The ignition voltage is between 9-17 volts.
4. The engine coolant temperature (ECT) is between -7 and +130°C (+20 and +254°F).
5. The engine has been running more than 5 seconds.
6. The throttle position (TP) has not increased more than 8 percent in 1 second.
7. The TP has not decreased more than 1.5 percent in 1 second.
8. DTC P0301, P0302, P0303, P0304 run continuously when the above conditions are met.

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

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

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

DTC P0301-P0304

The Crankshaft Position (CKP) system variation learn feature is used to calculate reference period errors caused by slight tolerance variations in the crankshaft, and the CKP sensor. The calculated error allows the powertrain control module (PCM) to accurately compensate for reference period variations. This enhances the ability of the PCM to detect misfire events over a wider range of engine speed and load. The PCM stores the CKP system variation values after a learn procedure has been performed. If the actual crankshaft position variation is not within the CKP system variation compensating values stored in the PCM, DTC P0300 may set. If the PCM detects that the CKP system variation values are not stored in the PCM memory, DTC P0315 sets.

This diagnostic procedure supports the following DTC

DTC P0315 Crankshaft Position (CKP) System Variation Not Learned

1. The engine is running.
2. DTC P0315 runs continuously once the above condition is met.

1. The CKP system variation values are not stored in the PCM memory.
2. The above condition is present for 0.5 second.

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

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

DTC P0315

The knock sensor (KS) system enables the powertrain control module (PCM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The KS is located on the intake side of the engine block. The KS produces an AC voltage signal that varies depending on the vibration level during engine operation. The PCM adjusts the spark timing based on the amplitude and the frequency of the KS signal. The PCM receives the KS signal through a signal circuit. The KS ground is supplied by the PCM through a low reference circuit. The PCM learns a minimum KS noise level at idle and uses calibrated values for the rest of the RPM range. The PCM should monitor a normal KS signal within the noise channel. If the PCM malfunctions in a manner that will not allow proper diagnosis of the KS system, or the KS signal is not present, DTC P0325 will set.

This diagnostic procedure supports the following DTC

DTC P0325 Knock Sensor (KS) Circuit

1. The engine speed is more than 1,800 RPM.
2. The engine load meets or exceeds a calibrated specification.
3. DTC P0325 runs continuously when the above conditions are met.

The average KS voltage is less than 0.01 volts or more than 4.9 volts for 8 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 P0325

The knock sensor (KS) system enables the powertrain control module (PCM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The KS is located on the intake side of the engine block. The KS produces an AC voltage signal that varies depending on the vibration level during engine operation. The PCM adjusts the spark timing based on the amplitude and the frequency of the KS signal. The PCM receives the KS signal through a signal circuit. The KS ground is supplied by the PCM through a low reference circuit. The PCM learns a minimum KS noise level at idle and uses calibrated values for the rest of the RPM range. The PCM should monitor a normal KS signal within the noise channel. When the PCM detects a KS signal that varies outside of the noise channel, the PCM will retard the spark timing until the knock goes away. If the PCM is operating on large amounts of spark retard and is unable to eliminate the knock, DTC P0326 will set.

This diagnostic supports the following DTC

DTC P0326 Knock Sensor (KS) Performance

1. The engine speed is more than 1,800 RPM.
2. The manifold absolute pressure (MAP) is more than 55 kPa
3. DTC P0326 runs continuously when the above conditions are met.

1. The KS signal indicates an engine knock is present.
2. The PCM commanded spark retard at a given engine load and speed is more than the calibrated value.
3. The above conditions exist for 8 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 P0326

The knock sensor (KS) system enables the powertrain control module (PCM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The KS is located on the intake side of the engine block. The KS produces an AC voltage signal that varies depending on the vibration level during engine operation. The PCM adjusts the spark timing based on the amplitude and the frequency of the KS signal. The PCM receives the KS signal through a signal circuit. The KS ground is supplied by the PCM through a low reference circuit. The PCM learns a minimum KS noise level at idle and uses calibrated values for the rest of the RPM range. The PCM should monitor a normal KS signal within the noise channel. If the PCM detects the KS signal outside of the noise channel, or the KS signal is not present, DTC P0327 will set.

This diagnostic supports the following DTC

DTC P0327 Knock Sensor (KS) Circuit Low Voltage

1. The engine speed is more than 1,800 RPM.
2. DTC P0327 runs continuously when the above conditions are met.

The maximum minus the minimum KS voltage is less than 0.06 volts for 8 seconds.

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

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

1. Inspect the KS for physical damage. A KS that is dropped or damaged may cause a DTC to set.
2. Inspect the KS for proper installation. A KS that is loose or over torqued may cause a DTC to set. The KS should be free of thread sealant. The KS mounting surface should be free of burrs, casting flash, and foreign material.
3. The KS must be clear of hoses, brackets, and engine electrical wiring.
4. For an intermittent condition, refer to «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis__intermittent-conditions) .

DTC P0327

The crankshaft position (CKP) sensor signal indicates the crankshaft speed and position. The CKP sensor produces an AC voltage of varying amplitude and frequency. The frequency depends on the velocity of the crankshaft, and the AC output voltage depends on crankshaft position and battery voltage. The CKP sensor works in conjunction with a 58-tooth reluctor wheel attached to the crankshaft. The powertrain control module (PCM) determines the crankshaft position by the reference gap. The PCM can synchronize the ignition timing, fuel injector timing, and the spark knock control based on the CKP sensor and the camshaft position (CMP) sensor inputs. The CKP sensor is also used to detect a misfire. The CKP sensor circuits connect directly to the PCM. The circuits between the CKP sensor and the PCM consists of the following

1. A CKP sensor signal
2. A low reference

If the PCM detects an incorrect number of pulses from the CKP sensor, DTC P0335 sets.

This diagnostic procedure supports the following DTC

DTC P0335 Crankshaft Position (CKP) Sensor Circuit

1. The engine is cranking or running.
2. DTC P0335 runs continuously once the above condition is met.

1. The PCM detects an incorrect number of CKP pulses during engine cranking for 4 seconds.
2. The PCM detects an incorrect number of CKP pulses while the engine is running 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.

For an intermittent condition, the vehicle may need to be operated within the conditions captured in the Freeze Frame/Failure Records. Inspect for one of the following conditions, if the code does set intermittently while operating within the conditions captured in the Freeze Frame/Failure Records. If one of the following conditions are not present, refer to Intermittent Conditions for inspections that would help aid in diagnosing an intermittent condition.

1. Damage to the CKP reluctor wheel
2. Incorrect sensor installation
3. The sensor coming in contact with the CKP reluctor wheel
4. A cracked or damaged sensor
5. Foreign material passing between the sensor and the CKP reluctor wheel

DTC P0335

The crankshaft position (CKP) sensor is a variable reluctance sensor. The CKP sensor indicates the crankshaft speed and position. The CKP sensor produces an AC voltage of different amplitude and frequency. The frequency depends on the velocity of the crankshaft. The AC voltage output depends on the crankshaft position and the battery voltage. The CKP sensor works in conjunction with a 58X reluctor wheel attached to the crankshaft. The CKP sensor is also used to detect misfire and tachometer display. The CKP sensor connects to the powertrain control module (PCM) through the following circuits

1. The CKP sensor signal circuit
2. The low reference circuit

If the PCM detects an excessive number of resyncs from the CKP sensor, DTC P0336 sets.

This diagnostic procedure supports the following DTC

DTC P0336 Crankshaft Position (CKP) Sensor Performance

1. The engine is running.
2. The engine speed is greater than 450 RPM.
3. DTC P0336 runs continuously when the above conditions are met.

The PCM detects 5 CKP resyncs within 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.

DTC P0336

The camshaft position (CMP) sensor provides the powertrain control module (PCM) with a signal representing the camshaft's rotational position. The CMP sensor is a hall effect switch that works in conjunction with a 4X reluctor wheel. The reluctor wheel consists of 4 pairs of rising and falling edges that are differently spaced. The CMP sensor produces a magnetic field. When the camshaft rotates, and the reluctor wheel edge passes by the CMP sensor, there is a change in the magnetic field. The PCM views each transition from low to high as one signal. The PCM receives 4 signals per camshaft revolution. The CMP sensor has the following circuits

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

The PCM supplies 5 volts to the CMP sensor on the 5-volt reference circuit, and provides a low reference circuit. The CMP sensor provides a 4X signal to the PCM on the signal circuit. If the PCM detects extra or missing CMP sensor signal transitions within a certain number of crankshaft revolutions, DTC P0340 will set.

This diagnostic procedure supports the following DTC

DTC P0340 Camshaft Position (CMP) Sensor Circuit

1. DTCs P0106, P0107, P0108, P0315, P0335, and P0336 are not set.
2. The engine is running.
3. The manifold absolute pressure (MAP) is more than 45 kPa.
4. This DTC runs continuously.

The PCM does not detect the signal of the CMP sensor for 3 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 P0340

See also:
• Engine Controls Schematics
• Powertrain Control Module (PCM) Connector End Views
• Engine Controls Connector End Views
• Diagnostic System Check - Vehicle
• Scan Tool Data List
• Testing for Intermittent Conditions and Poor Connections
• Circuit Testing
• Wiring Repairs
• Silicon Contamination of Heated Oxygen Sensors Notice
• Fuel System Diagnosis
• Connector Repairs
• Heated Oxygen Sensor (HO2S) Resistance Learn Reset Notice
• Control Module References
• Diagnostic Trouble Code (DTC) List - Vehicle
• Oil Consumption Diagnosis
• Loss of Coolant
• Probing Electrical Connectors
• DTC P0130
• Intermittent Conditions
• Altitude vs Barometric Pressure
• Symptoms - Engine Mechanical
• Testing for Continuity
• CKP System Variation Learn Procedure
• Crankcase Ventilation System Inspection/Diagnosis
• Ground Distribution Schematics
• Restricted Exhaust
• Special Tools
• Spark Plug Inspection
• DTC P0420
• Engine Controls Schematics
• Engine Controls Connector End Views
• Detonation/Spark Knock
• Detonation/Spark Knock
• Measuring Frequency
• Camshaft Cleaning and Inspection
• DTC P0135