Engine Controls - 2.0l (DTC P023A to p0131) Chevrolet Cobalt I

Circuit Description

The supercharger intercooler relay is a normally open relay. The relay armature is held in the open position by spring tension. The ignition 1 voltage is supplied directly to the relay coil and to the armature contact when the ignition is ON, or the engine is running. The powertrain control module (PCM) supplies the ground path to the relay coil control circuit via an internal integrated circuit called an output driver module (ODM). When the engine is running, the PCM commands the relay ON, and the relay coil creates an electromagnetic field. This electromagnetic field overcomes the spring tension and pulls the armature contact into the stationary contact of the relay load circuit. The closing of the relay contacts allow current to flow from the battery to the supercharger intercooler pump. When the ignition switch is turned to the OFF position, power is interrupted to the output driver module in the PCM and the relay electromagnetic field collapses. This allows the spring tension to separate the relay armature contact from the relay load circuit contact, which interrupts current flow to the supercharger intercooler pump.

If the PCM detects an improper voltage on the supercharger intercooler pump relay control circuit for more than 30 seconds, DTC P023A sets.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC P023A Charge Air Cooler (CAC) Coolant Pump Relay Control Circuit

Conditions for Running the DTC

1. The ignition is ON, or the engine is running.
2. The Ignition 1 Voltage parameter is between 11-18 volts.
3. DTC P023A runs continuously when the above conditions are met.

Conditions for Setting the DTC

The PCM detects an improper voltage on the supercharger intercooler pump relay control circuit for more than 30 seconds.

Action Taken When the DTC Sets

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

Conditions for Clearing the MIL/DTC

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

DTC P023A

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 monitors the voltage on the HO2S heater low control circuit for heater fault diagnosis. If the PCM detects that the HO2S heater low control circuit voltage is not within a specified range, DTC P0030 sets for HO2S 1, or DTC P0036 sets for HO2S 2.

DTC Descriptors

This diagnostic procedure supports the following DTCs

1. DTC P0030 HO2S Heater Control Circuit Sensor 1
2. DTC P0036 HO2S Heater Control Circuit Sensor 2

1. The Ignition 1 Signal parameter is between 11-18 volts.
2. The engine speed is more than 450 RPM.
3. DTC P0030 or P0036 run continuously when the above conditions are met.

1. The PCM detects that the affected HO2S heater low control circuit voltage is not within a specified range.
2. DTC P0030 or P0036 sets within 3 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 P0030 or P0036

Supercharger boost pressure is regulated to prevent engine and drive train damage. When the engine is operating under high boost conditions, the powertrain control module (PCM) limits boost pressure to 12 psi or less. The PCM disables boost under the following conditions

1. When reverse gear is selected
2. When the vehicle is decelerating
3. If an intercooler pump failure is detected
4. If the intake air temperature (IAT) sensor 2 becomes excessively high
5. If the engine coolant temperature (ECT) becomes excessively high
6. Under heavy load in first and second gear at engine speeds above 5,800 RPM
7. When drivetrain abuse is detected

The PCM controls boost pressure by pulse width modulation (PWM) of the boost control solenoid. The boost control solenoid is a normally open valve. Under most conditions, the PCM commands the boost control solenoid to operate at a 99-100 percent duty cycle. This keeps the solenoid valve closed and allows only inlet vacuum from the supercharger plenum to the bypass valve actuator to control the position of the bypass valve. At idle, engine vacuum is applied to the upper side of the bypass valve actuator, counteracting spring tension to hold the bypass valve open. When the engine load is increased, the engine vacuum is decreased, causing the spring in the bypass valve to overcome the diminishing applied vacuum, closing the bypass valve and allowing the boost pressure to increase. When reduced boost pressure is desired, the PCM commands the boost control solenoid to operate at a 0-98 percent duty cycle. This opens the solenoid valve and allows boost pressure to enter the bypass valve actuator at the lower side to counteract the spring tension, opening the bypass valve and recirculating excess boost pressure back into the supercharger inlet.

The PCM monitors the voltage level on the boost control solenoid control circuit. If the PCM detects an improper voltage level on the supercharger boost control solenoid control circuit, DTC P0033 sets.

This diagnostic procedure supports the following DTC

DTC P0033 Supercharger Bypass Valve Solenoid Control Circuit

1. The ignition is ON.
2. The engine is running.
3. The ignition 1 voltage is between 11-18 volts.
4. This DTC runs continuously within the enabling conditions.

The PCM detects an improper voltage level on the boost control solenoid control circuit 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.

Diagnostic Aids

1. For additional information, review the Boost Control System Description. Refer to «Boost Control System Description»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-introduction) .
2. If the condition is intermittent, refer to «Inducing Intermittent Fault Conditions»(/chevrolet/cobalt/i-2004-2010/remont/electrical-component-locations/#wiring-systems-electrical-power-management) and «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis__intermittent-conditions) .

DTC P0033

The powertrain control module (PCM) uses the following information to calculate an expected airflow rate

1. The throttle position (TP)
2. The barometric pressure (BARO)
3. The super charger inlet pressure (SCIP)
4. The intake air temperature (IAT)
5. The mass air flow (MAF)
6. The engine RPM

If the PCM detects the airflow rate is more than expected, DTC P0068 sets.

This diagnostic procedure supports the following DTC

DTC P0068 Throttle Body Airflow Performance

1. The engine is running and the engine speed is more than 800 RPM.
2. DTC P0068 runs continuously when the above conditions are met.

The PCM detects that the manifold absolute pressure (MAP) and MAF does not match calculated air flow for more than 0.2 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 has run and passed.
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.

Test Description

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

1. 6: This step will determine if the SCIP sensor voltage is within the proper range with the key ON, engine OFF.
2. 7: This step will determine if the sensor responds properly to the change in super charger inlet pressure.
3. 10: When the PCM detects a condition within the ETC system, other DTCs may set due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Keep this in mind when reviewing captured DTC info.

DTC P0068

The barometric pressure (BARO) sensor measures the pressure of the atmosphere. This pressure is affected by altitude and weather conditions. A diaphragm within the BARO sensor is displaced by the pressure changes that occur from varying altitudes and weather conditions. The sensor translates this diaphragm action into the voltage signal input that is used by the powertrain control module (PCM) for diagnostics and emissions control.

The supercharger inlet pressure (SCIP) sensor measures both the atmospheric pressure and the vacuum that exists under different operating conditions in the supercharger intake plenum. The plenum volume between the throttle body (TB) and the supercharger is where this sensor is located, and for the purpose of this diagnostic, this area is considered to be the intake manifold. The diaphragm within the SCIP sensor functions in the same manner as the BARO sensor. The sensors are not interchangeable. The actual measurement from the SCIP sensor is used by the PCM to calculate the difference continuously between BARO and SCIP. The calculated difference is displayed as the SC Inlet Pressure parameter.

The purpose of this diagnostic is to analyze the correlation between the BARO sensor, and the SCIP sensor. This is accomplished by comparing the difference between BARO and SCIP at key ON, engine OFF (KOEO), at closed throttle idle conditions, and at wide open throttle update events. At KOEO the difference between BARO and SCIP is represented on the scan tool by the SC Inlet Pressure parameter as a value that should be very close to zero. A negative SC Inlet Pressure parameter means that the BARO sensor value is less than the SCIP value. A positive SC Inlet Pressure parameter represents a BARO sensor value that is more than the SCIP value.

At idle the SC Inlet Pressure parameter represents the calculated difference between BARO and the reduced pressure that is present in the supercharger intake plenum as a positive value. At wide open throttle the SC Inlet Pressure parameter represents the calculated difference between BARO and the increased pressure that is present in the supercharger intake plenum, and should be very close to zero.

Both sensors have the following types of circuits

1. A PCM supplied and regulated 5-volt reference circuit
2. A PCM supplied ground for the low reference circuit
3. A sensor signal circuit that supplies a voltage input to the PCM

Changes in BARO due to weather are relatively small, while changes due to altitude are significant. Pressure can range from 56 kPa at an altitude of 4267 meters (14,000 feet), to 104 kPa at or below sea level.

If the PCM detects that the BARO sensor signal and the SCIP sensor signal are not within a calibrated range of each other, whether that value is negative or positive, DTC P0069 sets.

This diagnostic procedure supports the following DTC

DTC P0069 Supercharger Inlet Pressure (SCIP) - Barometric (BARO) Pressure Correlation

1. DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0120, P0121, P0125, P0128, P0220, P0502, P1182, P1183, P1184, P1516, P2101, P2227, P2228, P2229 are not set.
2. The ignition is ON. OR
3. The engine is running.
4. DTC P0069 runs continuously when the above conditions are met.

1. The PCM detects that during ignition ON, with the engine OFF, the calculated difference between BARO and SCIP, whether that value is negative or positive, is more than 12 kPa for more than 30 seconds. OR
2. The PCM has detected that a wide open throttle update event has occurred within the previous 2 kilometers (1.2 miles) and the difference between BARO, and a calculated BARO using the SCIP sensor, is more than 12 kPa for more than 30 seconds. OR
3. The PCM has not detected a wide open throttle update event within the previous 2 kilometers (1.2 miles) and the difference between BARO, and a calculated BARO using the SCIP sensor, is more than 60 kPa for more than 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 P0069

The intake air temperature (IAT) sensor 2 is a variable resistor. The IAT sensor 2 has a signal circuit and a low reference circuit. The IAT sensor 2 measures the temperature of the air entering the induction system. 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 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 P0097 sets.

This diagnostic procedure supports the following DTC

DTC P0097 Intake Air Temperature (IAT) Sensor 2 Circuit Low Voltage

1. DTCs P0117, P0118, P0502, and P0503 are not set.
2. The engine run time is more than 10 seconds.
3. The vehicle speed sensor (VSS) indicates that vehicle speed is more than 40 km/h (25 mph).
4. The engine coolant temperature (ECT) is less than 110°C (230°F).
5. This DTC runs continuously within the enabling conditions in a 250 ms loop.

The PCM detects that the IAT sensor 2 parameter is more than 149°C (300°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.

DTC P0097

The intake air temperature (IAT) sensor 2 is a variable resistor. The IAT sensor 2 has a signal circuit and a low reference circuit. The IAT sensor 2 measures the temperature of the air entering the induction system. 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 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 P0098 sets.

This diagnostic procedure supports the following DTC

DTC P0098 Intake Air Temperature (IAT) Sensor 2 Circuit High Voltage

1. DTCs P0101, P0102, P0103, P0117, P0118, P0502, and P0503 are not set.
2. The engine run time is more than 10 seconds.
3. The vehicle speed sensor (VSS) indicates that vehicle speed is less than 1.6 km/h (1 mph).
4. The engine coolant temperature (ECT) is more than 50°C (122°F).
5. The mass air flow (MAF) is less than 12 g/s.
6. This DTC runs continuously within the enabling conditions in a 250 ms loop.

The PCM detects that the IAT Sensor 2 parameter is less than -39°C (-38°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.

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 P0098

The intake airflow system performance diagnostic provides the within-range rationality check for the mass air flow (MAF), supercharger inlet pressure (SCIP), and the throttle position (TP) sensors. This is an explicit model-based diagnostic containing 3 separate models for the intake system.

1. One model, the throttle model, describes the flow through the throttle body and is used to estimate the MAF through the throttle body as a function of barometric pressure (BARO), throttle position, intake air temperature (IAT), and estimated SCIP.
2. Another model, the first intake manifold model, describes the intake manifold and is used to estimate SCIP as a function of the MAF into the intake manifold from the throttle body and the MAF out of the intake manifold caused by engine pumping. The flow into the intake manifold from the throttle uses the MAF estimate calculated from the above throttle model.
3. Another model is the second intake manifold model and is identical to the first intake manifold model except that the MAF sensor measurement is used instead of the throttle model estimate for the throttle air input.
4. Finally, a fourth model is created from the combination and additional calculations of the throttle model and the first intake manifold model.

The estimates of MAF, SCIP, and TP that are obtained from this system of models and calculations are then compared to the actual measured values from the MAF, SCIP, and the TP sensors and to each other to determine the appropriate DTC to fail. The following table illustrates the possible failure combinations and the resulting DTC or DTCs.

DTC P0101

If the powertrain control module (PCM) detects that the actual measured airflow from MAF, SCIP, and TP is not within range of the calculated airflow that is derived from the system of models, DTC P0101 sets.

This diagnostic procedure supports the following DTC

DTC P0101 Mass Air Flow Sensor Performance

1. DTCs P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0335, P0336, P1183, P1184, P2228, P2229 are not set.
2. The engine speed is between 400-6,400 RPM.
3. The IAT Sensor 1 parameter is between -7°C and +125°C (+19°F and +257°F).
4. The ECT Sensor parameter is between 70-125°C (158-257°F).
5. This DTC runs continuously within the enabling conditions.

The PCM detects that the actual measured airflow from the MAF, SCIP, and TP is not within range of the calculated airflow that is derived from the system of models for more than 0.5 second.

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

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

1. Any condition that can cause the MAF, SCIP, and TP sensors to be shifted in value at the same time will cause this DTC to set.
2. A wide open throttle (WOT) acceleration from a stop should cause the MAF sensor parameter on the scan tool to increase rapidly. This increase should be from 3-6 g/s at idle to 180 g/s or more at the time of the 2-3 shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust system.
3. A skewed or stuck engine coolant temperature (ECT) or IAT sensor 1 will cause the calculated models to be inaccurate and may cause this DTC to run when it should not.
4. A skewed MAP sensor may cause this DTC to set.
5. A steady or intermittent high resistance of 15 ohms or more on the ignition 1 voltage circuit will cause the MAF sensor values to be skewed high by up to 60 gs, and may cause this DTC to set. A high resistance will cause a driveability concern before this DTC sets.
6. The BARO that is used by the PCM to calculate the airflow models is initially based on the BARO sensor at key ON. With the ignition ON and the engine OFF, the BARO Sensor parameter varies with the altitude. 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. Refer to «Altitude vs Barometric Pressure»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-introduction__altitude-vs-barometric-pressure) .
7. If the condition is intermittent, refer to «Inducing Intermittent Fault Conditions»(/chevrolet/cobalt/i-2004-2010/remont/electrical-component-locations/#wiring-systems-electrical-power-management) and «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis__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: The SC Inlet Pressure parameter is the difference between BARO and SCIP, and at key ON, engine OFF (KOEO) should be close to zero.
3. 14: This voltage drop test will determine if high resistance has caused this DTC to set.
4. 16: This step verifies the voltage signal from the PCM to the MAF sensor connector.
5. 17: This step will determine if the MAF sensor is able to generate a frequency signal.
6. 18: This step will determine if an abnormal resistance or a short to the IAT signal circuit has skewed the MAF sensor frequency signal.

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 the inlet air flow through the sensor bore. The frequency varies within a range of near 2,000 Hertz at idle to near 10,000 Hertz at maximum engine load. If the PCM detects the frequency signal is less than the possible range of a correctly operating MAF sensor, DTC P0102 sets.

This diagnostic procedure supports the following DTC

DTC P0102 Mass Air Flow (MAF) Sensor Circuit Low Frequency

1. The engine is running for more than 5 seconds.
2. The engine speed is more than 500 RPM.
3. The ignition 1 signal is more than 11 volts.
4. The above conditions are met for more than 2.5 seconds.
5. This DTC runs continuously within the enabling conditions.

The PCM detects that the MAF sensor frequency signal is less than 100 Hertz for more than 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.

1. Inspect for any contamination or debris on the sensing elements of the MAF sensor.
2. A wide open throttle (WOT) acceleration from a stop should cause the MAF sensor parameter on the scan tool to increase rapidly. This increase should be from 2-6 g/s at idle to 180 g/s or more at the time of the 2-3 shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust system.
3. A high resistance of 15 ohms or more on the ground circuit or the ignition 1 circuit of the MAF sensor may cause this DTC to set. A high resistance will cause a driveability concern before this DTC sets.
4. If the condition is intermittent, refer to «Inducing Intermittent Fault Conditions»(/chevrolet/cobalt/i-2004-2010/remont/electrical-component-locations/#wiring-systems-electrical-power-management) and «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis__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 MAF sensor is able to generate a frequency signal.
6. 13: This step will determine which portion of the circuit or which component is shorted to ground.
7. 16: 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 10,000 Hertz at maximum engine load. If the PCM detects a frequency signal that is more than the possible range of a correctly operating MAF sensor, DTC P0103 sets.

This diagnostic procedure supports the following DTC

DTC P0103 Mass Air Flow (MAF) Sensor Circuit High Frequency

1. The engine is running for more than 5 seconds.
2. The engine speed is more than 500 RPM.
3. The ignition 1 signal is more than 11 volts.
4. The above conditions are met for more than 2.5 seconds.
5. This DTC runs continuously within the enabling conditions.

The PCM detects that the MAF sensor frequency signal is more than 11,000 Hertz for more than 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.

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 at the fuse for the ignition 1 voltage circuit of the MAF sensor may cause this DTC to set.
3. If the condition is intermittent, refer to «Inducing Intermittent Fault Conditions»(/chevrolet/cobalt/i-2004-2010/remont/electrical-component-locations/#wiring-systems-electrical-power-management) and «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis__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 may indicate an EMI related fault or a poor connection at the PCM. Disconnecting the MAF sensor may set additional related DTCs.
2. 5: This step determines if incorrect harness routing has caused this DTC to set.
3. 6: This step determines if water intrusion has caused this DTC to set.
4. 7: This step determines if high resistance at any point in the ignition 1 voltage circuit has caused this DTC to set.

DTC P0103

The manifold absolute pressure (MAP) sensor that resides in the engine intake manifold is integrated with the intake air temperature (IAT) sensor 2. The purpose of this integrated sensor is to measure the following

1. The atmospheric pressure and the vacuum or the reduced pressure that exists under different operating conditions in the engine intake manifold
2. The supercharged air pressure that exists under high load or wide open throttle conditions in the engine intake manifold
3. The IAT sensor 2 after the supercharger and the intercooler as it enters the engine intake manifold
4. The IAT sensor 2 after the supercharger bypass valve and the intercooler as it enters the engine intake manifold

The MAP/IAT sensor 2 has the following types of circuits

1. A powertrain control module (PCM) supplied and regulated MAP 5-volt reference circuit
2. A PCM supplied ground for the low reference circuit that is shared by the MAP and the IAT sensor 2
3. A MAP sensor signal circuit that supplies a voltage input to the PCM
4. A PCM supplied 5-volt, IAT signal circuit

The diaphragm within the MAP sensor responds to all of the various pressure changes in the intake manifold and provides a signal voltage to the PCM on the signal circuit relative to those pressure changes.

The PCM monitors the MAP sensor signal for voltage that is outside of the normal range of a properly operating sensor. If the PCM detects a MAP sensor signal that is not within range of a calibrated limit of the estimated value, DTC P0106 sets.

This diagnostic procedure supports the following DTC

DTC P0106 Manifold Absolute Pressure (MAP) Sensor Performance

1. DTCs P0107, P0108, P0120, P0121, P0220, P0506, P0507, P2135 are not set.
2. The engine speed is between 400-6,400 RPM.
3. The engine coolant temperature (ECT) is between 70-125°C (158-257°F).
4. The IAT is between -7 to +125°C (+19 to +257°F).
5. The change in throttle position (TP) is less than 5 percent.
6. The above enabling criteria must be stable for more than 5 seconds.
7. DTC P0106 runs continuously when the above conditions are met.

The PCM detects that the MAP sensor signal is 25 kPa more than the calibrated estimate for more than 90 seconds.

OR

The PCM detects that the MAP sensor signal is 45 kPa less than the calibrated estimate for more than 90 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 P0106

The manifold absolute pressure (MAP) sensor that resides in the engine intake manifold is integrated with the intake air temperature (IAT) sensor 2. The purpose of this integrated sensor is to measure the following

1. The atmospheric pressure and the vacuum or the reduced pressure that exists under different operating conditions in the engine intake manifold
2. The supercharged air pressure that exists under high load or wide open throttle conditions in the engine intake manifold
3. The IAT 2 after the supercharger and the intercooler as it enters the engine intake manifold
4. The IAT 2 after the supercharger bypass valve and the intercooler as it enters the engine intake manifold

The MAP/IAT sensor 2 has the following types of circuits

1. A powertrain control module (PCM) supplied and regulated MAP 5-volt reference circuit
2. A PCM supplied ground for the low reference circuit that is shared by the MAP and the IAT sensor 2
3. A MAP sensor signal circuit that supplies a voltage input to the PCM
4. A PCM supplied 5-volt, IAT signal circuit

The diaphragm within the MAP sensor responds to all of the various pressure changes in the intake manifold, and provides a signal voltage to the PCM on the signal circuit, relative to those pressure changes.

The PCM monitors the MAP sensor signal for voltage that is outside of the normal range of a properly operating sensor. If the PCM detects a MAP sensor signal voltage that is excessively low, DTC P0107 sets.

This diagnostic procedure supports the following DTC

DTC P0107 Manifold Absolute Pressure (MAP) Sensor Circuit Low Voltage

1. DTCs P0120, P0121, P0220, P2135 are not set.
2. The ignition is ON, or the engine is cranking or running.
3. The TP Indicated Angle parameter is more than 0 percent, when the engine speed is less than 1,100 RPM. OR
4. The TP Indicated Angle parameter is more than 10 percent, when the engine speed is more than 1,100 RPM.
5. DTC P0107 runs continuously when the above conditions are met.

The PCM detects that the MAP sensor signal voltage is less than 0.1 volts for more than 2 seconds.

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

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

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

1. 2: The MAP sensor 5-volt reference circuit is shared with other sensors. If DTC P0651 is set, this indicates a shorted 5-volt reference circuit or a shorted component, and should be diagnosed first.

DTC P0107

The manifold absolute pressure (MAP) sensor that resides in the engine intake manifold is integrated with the intake air temperature (IAT) sensor 2. The purpose of this integrated sensor is to measure the following

1. The atmospheric pressure and the vacuum or the reduced pressure that exists under different operating conditions in the engine intake manifold
2. The supercharged air pressure that exists under high load or wide open throttle conditions in the engine intake manifold
3. The IAT 2 after the supercharger and the intercooler as it enters the engine intake manifold
4. The IAT 2 after the supercharger bypass valve and the intercooler as it enters the engine intake manifold

The MAP/IAT sensor 2 has the following types of circuits

1. A powertrain control module (PCM) supplied and regulated MAP 5-volt reference circuit
2. A PCM supplied ground for the low reference circuit that is shared by the MAP and the IAT sensor 2
3. A MAP sensor signal circuit that supplies a voltage input to the PCM
4. A PCM supplied 5-volt, IAT signal circuit

The diaphragm within the MAP sensor responds to all of the various pressure changes in the intake manifold, and provides a signal voltage to the PCM on the signal circuit, relative to those pressure changes.

The PCM monitors the MAP sensor signal for voltage that is outside of the normal range of a properly operating sensor. If the PCM detects a MAP sensor signal voltage that is excessively high, DTC P0108 sets.

This diagnostic procedure supports the following DTC

DTC P0108 Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage

1. DTCs P0120, P0121, P0220, P2135 are not set.
2. The engine has been running for a calibrated length of time, that is determined by the start-up engine coolant temperature (ECT). The length of time ranges from 2 minutes at less than -30°C (-22°F) to 1 second at more than 30°C (86°F).
3. The TP Indicated Angle parameter is less than 90 percent, when the engine speed is less than 1,000 RPM. OR
4. The TP Indicated Angle parameter is less than 98 percent, when the engine speed is more than 1,000 RPM.
5. DTC P0108 runs continuously when the above conditions are met.

The PCM detects that the MAP sensor signal voltage is more than 4.90 volts for more than 2 seconds.

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

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

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

1. 2: The MAP sensor 5-volt reference circuit is shared with other sensors. If DTC P0651 is set, this indicates a shorted 5-volt reference circuit, or a shorted component, and should be diagnosed first.

DTC P0108

The intake air temperature (IAT) sensor 1 is a variable resistor. The IAT sensor 1 has a signal circuit and a low reference circuit. The IAT sensor 1 measures the temperature of the air entering the induction system. 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.

This diagnostic procedure supports the following DTC

DTC P0112 Intake Air Temperature (IAT) Sensor 1 Circuit Low Voltage

1. DTCs P0117, P0118, P0502, and P0503 are not set.
2. The engine run time is more than 10 seconds.
3. The vehicle speed sensor (VSS) indicates that vehicle speed is more than 40 km/h (25 mph).
4. The engine coolant temperature (ECT) is less than 110°C (230°F).
5. This DTC runs continuously within the enabling conditions.

The PCM detects that the IAT sensor 1 parameter is more than 149°C (300°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.

DTC P0112

The intake air temperature (IAT) sensor 1 is a variable resistor. The IAT sensor 1 has a signal circuit and a low reference circuit. The IAT sensor 1 measures the temperature of the air entering the induction system. 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.

This diagnostic procedure supports the following DTC

DTC P0113 Intake Air Temperature (IAT) Sensor 1 Circuit High Voltage

1. DTCs P0101, P0102, P0103, P0117, P0118, P0502, and P0503 are not set.
2. The engine run time is more than 10 seconds.
3. The vehicle speed sensor (VSS) indicates that vehicle speed is less than 1.6 km/h (1 mph).
4. The engine coolant temperature (ECT) is more than 50°C (122°F).
5. The mass air flow (MAF) is less than 12 g/s.
6. This DTC runs continuously within the enabling conditions.

The PCM detects that the IAT sensor 1 parameter is less than -39°C (-38°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.

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 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.

This diagnostic procedure supports the following DTC

DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage

1. The engine is running for more than 10 seconds. OR
2. The ignition is ON, and the intake air temperature (IAT) is less than 70°C (158°F). OR
3. The ignition is OFF, but the PCM has not powered down.
4. This DTC runs continuously within the enabling conditions in a 1-second loop.

The PCM detects that the ECT sensor parameter is more than 149°C (300°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.

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.

This diagnostic procedure supports the following DTC

DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage

1. The engine is running for more than 1 minute. OR
2. The ignition is ON, and the intake air temperature (IAT) is more than -7°C (19°F). OR
3. The ignition is OFF, but the PCM has not powered down.
4. This DTC runs continuously within the enabling conditions in a 1-second loop.

The PCM detects that the ECT sensor parameter is less than -39°C (-38°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.

DTC P0118

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 1 signal voltage is not within the predicted range, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0120 Throttle Position (TP) Sensor 1 Circuit

1. The ignition switch is in the Unlock, Accessory, Crank, or Run position.
2. DTC P0641 is not set.
3. The ignition voltage is greater than 5.23 volts.
4. DTC P0120 runs continuously when the above conditions are met.

TP sensor 1 voltage is less than 0.27 volt or more than 4.73 volts for more than 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 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 P0120

The powertrain control module (PCM) uses the following information to calculate an expected airflow rate

1. The throttle position (TP)
2. The barometric pressure (BARO)
3. The manifold absolute pressure (MAP)
4. The intake air temperature (IAT)
5. The mass air flow (MAF)
6. The engine RPM

If the PCM detects the airflow rate is more than expected, DTC P0121 sets.

This diagnostic procedure supports the following DTC

DTC P0121 Throttle Position (TP) Sensor 1 Performance

1. DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0128, P0335, P0336, P0641, P0651, P1516, P2101, P2119, P2176 are not set.
2. The engine is running and the engine speed is more than 600 RPM.
3. The engine temperature is between 50-125°C (122-257°F).
4. The intake air temperature is between -7 to +125°C (+19 to +257°F).
5. DTC P0121 runs continuously when the above conditions are met.

The PCM detects that the calculated airflow rate is more than expected for more than 10 seconds.

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

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

1. 5: This step will determine if the MAP sensor voltage is within the proper range at idle.
2. 6: This step will determine if the MAP sensor responds properly to the change in manifold pressure.
3. 9: When the PCM detects a condition within the electronic throttle control (ETC) system other DTCs may set due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Keep this in mind when reviewing captured DTC info.

DTC P0121

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

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 the throttle plate movement. The TP sensor 1 signal voltage at closed throttle is near the 5-volt reference circuit and decreases as the throttle plate is opened. The TP sensor 2 signal voltage at closed throttle is near the low reference circuit and increases as the throttle plate is opened. If the PCM detects that the TP sensor 1 signal voltage is less than the predicted range, DTC P0122 sets.

This diagnostic procedure supports the following DTC

DTC P0122 Throttle Position (TP) Sensor 1 Circuit Low 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 greater than 5.23 volts.
4. DTC P0122 runs continuously when the above conditions are met.

The PCM detects that the TP sensor 1 voltage is less than 0.27 volt 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 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 P0122

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

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 the throttle plate movement. The TP sensor 1 signal voltage at closed throttle is near the 5-volt reference circuit and decreases as the throttle plate is opened. The TP sensor 2 signal voltage at closed throttle is near the low reference circuit and increases as the throttle plate is opened. If the PCM detects that the TP sensor 1 signal voltage is more than the predicted range, DTC P0123 sets.

This diagnostic procedure supports the following DTC

DTC P0123 Throttle Position (TP) Sensor 1 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 greater than 5.23 volts.
4. DTC P0123 runs continuously when the above conditions are met.

The PCM detects that the TP sensor 1 voltage is more than 4.73 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 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 P0123

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 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 the Closed Loop temperature, the diagnostics that use engine coolant temperature as enabling criteria may not run when expected.

If the PCM detects the calibrated amount of air flow and engine run time have been met, and the engine coolant has not met the Closed Loop temperature, DTC P0125 sets.

This diagnostic procedure supports the following DTC

DTC P0125 Engine Coolant Temperature (ECT) Insufficient For Closed Loop Fuel Control

1. DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0502, P0503 are not set.
2. The minimum air temperature is more than -7°C (+19°F).
3. The start-up engine coolant temperature (ECT) is less than 8°C (46°F).
4. The engine run time is between 30 seconds and 30 minutes.
5. The vehicle has traveled more than 0.8 kilometers (0.5 miles) at more than 8 km/h (5 mph).
6. The mass air flow (MAF) is between 20-75 g/s, with the average more than 30 g/s.
7. This DTC runs once per ignition cycle within the enabling conditions in a one second loop.

1. The calibrated amount of air flow has been met.
2. The calibrated amount of engine run time has been met.
3. The calibrated vehicle speed and distance have been met.
4. The minimum ECT for Closed Loop of 8°C (46°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, the diagnostics that use ECT as enabling criteria may not run when expected.

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.

This diagnostic procedure supports the following DTC

DTC P0128 Engine Coolant Temperature (ECT) Below Thermostat Regulating Temperature

1. DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0502, P0503 are not set.
2. The startup ECT is less than 80°C (176°F).
3. The intake air temperature (IAT) is more than -7°C (+19°F).
4. The engine run time is between 30 seconds and 30 minutes.
5. The vehicle is driven more than 0.8 kilometers (0.5 miles) at more than 8 km/h (5 mph).
6. The mass air flow (MAF) is between 20-75 g/s, with the average more than 30 g/s.
7. This DTC runs once per ignition cycle within the enabling conditions in a 1-second loop.

The PCM detects that

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 ECT of 80°C (176°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 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 the loop status is open too long, DTC P0130 will set.

This diagnostic procedure supports the following DTC

DTC P0130 HO2S Circuit Sensor 1

1. DTCs P0030, P0068, P0069, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0125, P0128, P0130, P0131, P0132, P0133, P0134, P0135, P0201, P0202, P0203, P0204, P0220, P1133, P1516, P1681, P2101, P2135, P2176 are not set.
2. The Engine Run Time parameter is more than 200 seconds.
3. The Engine Speed parameter is between 1,000-3,400 RPM.
4. The Ignition 1 Signal parameter is between 11-18 volts.
5. The Mass Airflow (MAF) Sensor parameter is between 10-50 g/s.
6. The Engine Coolant Temperature (ECT) Sensor parameter is more than 50°C (122°F).
7. The traction control is not active.
8. The catalyst protection mode is not active.
9. Decel fuel cut-off is not active.
10. Power enrichment is not active.
11. DTC P0130 runs continuously when the above conditions are met for 2 seconds.

1. The PCM detects that the Loop Status parameter is open.
2. DTC P0130 sets within 50 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: An HO2S heater fault may set this DTC.

DTC P0130

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 1.

This diagnostic procedure supports the following DTC

DTC P0131 HO2S Circuit Low Voltage Sensor 1

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) Indicated Angle parameter is between 15-30 percent.
6. The catalyst diagnostic test is not active.
7. No fuel injectors are disabled.
8. Traction control is not active.
9. The air/fuel ratio is between 14.5-14.8.
10. DTC P0131 runs the lean test continuously when the above conditions are 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 Ignition 1 Signal parameter is between 11-18 volts.
3. The Fuel Level Sensor parameter is more than 10 percent.
4. Power enrichment mode is enabled.
5. The Engine Run Time parameter is more than 200 seconds.
6. The catalyst diagnostic test is not active.
7. No fuel injectors are disabled.
8. Traction control is not active.
9. DTC P0131 runs the power enrichment test continuously when the above conditions are met for 2 seconds.

Lean Test

1. The PCM detects that the HO2S 1 Voltage parameter is less than 50 mV.
2. DTC P0131 sets within 100 seconds during the lean test when the above condition is met.

Power Enrichment Test

1. The PCM detects that the HO2S 1 Voltage parameter is less than 700 mV.
2. DTC P0131 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.
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

See also:
• Power Distribution Schematics
• Engine Controls Schematics
• Power and Grounding Connector End Views
• Powertrain Control Module (PCM) Connector End Views
• Diagnostic System Check - Vehicle
• Testing for Intermittent Conditions and Poor Connections
• Powertrain Relay Diagnosis
• Connector Repairs
• Circuit Testing
• Wiring Repairs
• Testing for Short to Ground
• Control Module References
• Diagnostic Trouble Code (DTC) List - Vehicle
• Engine Controls Connector End Views
• Probing Electrical Connectors
• Heated Oxygen Sensor (HO2S) Resistance Learn Reset Notice
• Intermittent Conditions
• Measuring Voltage
• Measuring Voltage Drop
• Troubleshooting with a Digital Multimeter
• Altitude vs Barometric Pressure
• DTC P2227
• DTC P1182
• Temperature vs Resistance
• Restricted Exhaust
• Using Connector Test Adapters
• Measuring Frequency
• Checking Aftermarket Accessories
• Engine Compression Test
• Timing Chain, Sprockets, and/or Tensioner Replacement
• Draining and Filling Cooling System (2.0L (LSJ))
• Thermostat Diagnosis
• DTC P0135
• Scan Tool Data List
• Silicon Contamination of Heated Oxygen Sensors Notice
• DTC P0101