Engine Controls - 4.8l, 5.3l & 6.0l (DTC p0420-p1125) Chevrolet Cab & Chassis Silverado 3500

Circuit Description

The three-way catalytic converter (TWC) reduces emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx). The catalyst within the converter promotes a chemical reaction, which oxidizes the HC and CO that are present in the exhaust gas. This process converts these chemicals into water vapor and carbon dioxide (CO2), and will reduce the NOx, by converting them into nitrogen. The catalytic converter also stores oxygen. The powertrain control module (PCM) monitors this process using heated oxygen sensor (HO2S) bank 1 sensor 2 and HO2S bank 2 sensor 2, located in the exhaust stream after the TWC. These sensors are referred to as the catalyst monitor sensors. The catalyst monitor sensors produce an output signal the PCM uses to indicate the oxygen storage capacity of the catalyst. This determines the catalysts ability to effectively convert the exhaust emissions.

If the catalyst is functioning correctly, the HO2S bank 1 sensor 2 and HO2S bank 2 sensor 2 signals will be far less active than the signals that are produced by HO2S bank 1 sensor 1 and HO2S bank 2 sensor 1. This indicates that the TWC oxygen storage capacity is at an acceptable threshold. When the response time of the catalyst monitor sensors are close to that of the fuel control sensors, the ability of the catalyst to store oxygen may be below an acceptable threshold.

The PCM performs this diagnostic test at idle. When the conditions for running this DTC are met, the following conditions occur

1. The air-to-fuel ratio transitions from lean to rich.
2. The air-to-fuel ratio transitions from rich to lean, opposite the first air-to-fuel ratio transition.
3. The PCM captures the response time of the front and the rear HO2S when the air-to-fuel ratio transitions occur. The HO2S response time changes from less than 350 mV to greater than 600 mV, and from greater than 600 mV to less than 350 mV.
4. The PCM measures the time necessary for the rear HO2S voltage to cross a reference lean-to-rich threshold, and the time necessary for the front HO2S voltage to cross the same lean-to-rich threshold. The difference between the front HO2S time and the rear HO2S time indicates the oxygen storage capacity of the catalyst. If the PCM detects that this time difference is less than a predetermined value, DTC P0420 for bank 1 or DTC P0430 for bank 2 sets.

DTC Descriptors

This diagnostic procedure supports the following DTCs

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

Conditions for Running the DTC

1. DTCs P0053, P0054, P0059, P0060, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0128, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0157, P0158, P0160, P0161, P0171, P0172, P0174, P0175, P0178, P0179, P0200, P0220, P0300, P0335, P0336, P0341, P0342, P0343, P0351-P0358, P0442, P0443, P0446, P0449, P0452, P0453, P0455, P0496, P0500, P0502, P0503, P0506, P0507, P1125, P1133, P1134, P1153, P1154, P1258, P1516, P2101, P2108, P2120, P2121, P2125, P2135, P2A01, P2A04 are not set.
2. The engine has been running for more than 10 minutes.
3. The intake air temperature (IAT) is between -20°C and +85°C (-4°F and +185°F).
4. The barometric pressure (BARO) is greater than 70 kPa.
5. The engine coolant temperature (ECT) is more than 70°C-120°C (158°F-248°F).
6. Since the end of the last idle period, the engine speed has been greater than 750 RPM for 39 seconds.
7. The engine must be at a stable idle speed, within 200 RPM of desired idle.
8. The battery voltage is greater than 11 volts.
9. The Closed Loop fuel control is enabled.
10. This diagnostic attempts up to one test during each valid idle period when the above conditions have been met for 3.5 seconds. This diagnostic attempts up to 12 tests during each drive cycle.

Conditions for Setting the DTC

1. The PCM determines that the oxygen storage capability of the TWC has degraded to less than a calibrated threshold.
2. This diagnostic may conclude in only one test attempt. However this diagnostic may require as many as 18 test attempts, which would require 3 ignition cycles. Each test attempt occurs within 1.5 minutes.

Action Taken When the DTC Sets

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

Conditions for Clearing the MIL/DTC

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

Diagnostic Aids

1. The catalyst test may abort due to a change in the engine load. Do not change the engine load, ensure the AC is OFF, the coolant fan is not cycling, while a catalyst test is in progress.
2. Driving the vehicle under the conditions outlined in the Inspection/Maintenance (I/M) section can verify whether the fault is present.
3. These conditions may cause a catalytic converter to degrade. Inspect for the following conditions: An engine misfire High engine oil or high coolant consumption Retarded spark timing A weak or poor spark A lean fuel mixture A rich fuel mixture A damaged oxygen sensor or wiring harness If an intermittent condition cannot be duplicated, the information included in Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC was set.
4. The catalyst may have been temporarily contaminated with a chemical from a fuel additive, fuel contamination, or any of the above conditions.

If the condition is determined to be intermittent, refer to Testing for Intermittent Conditions and Poor Connections .

Test Description

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

1. 5: A catalytic converter which has been discolored may be due to an engine running rich, lean or had a previous misfire. Verifying the fuel trim percentages may be of assistance in determining if such a condition exists.
2. 6: This steps inspects for conditions than can cause the TWC efficiency to appear degraded.

DTC P0420 or P0430 (Without HP2)

The three-way catalytic converter (TWC) reduces emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx). The catalyst within the converter promotes a chemical reaction, which oxidizes the HC and CO that are present in the exhaust gas. This process converts these chemicals into water vapor and carbon dioxide (CO2), and will reduce the NOx, by converting them into nitrogen. The catalytic converter also stores oxygen. The powertrain control module (PCM) monitors this process using heated oxygen sensor (HO2S) bank 1 sensor 2 and HO2S bank 2 sensor 2, located in the exhaust stream after the TWC. These sensors are referred to as the catalyst monitor sensors. The catalyst monitor sensors produce an output signal the PCM uses to indicate the oxygen storage capacity of the catalyst. This determines the catalysts ability to effectively convert the exhaust emissions.

If the catalyst is functioning correctly, the HO2S bank 1 sensor 2 and HO2S bank 2 sensor 2 signals will be far less active than the signals that are produced by HO2S bank 1 sensor 1 and HO2S bank 2 sensor 1. This indicates that the TWC oxygen storage capacity is at an acceptable threshold. When the response time of the catalyst monitor sensors are close to that of the fuel control sensors, the ability of the catalyst to store oxygen may be below an acceptable threshold.

The PCM performs this diagnostic during a commanded lean-to-rich air-to-fuel ratio change following a period of deceleration fuel cut-off (DFCO). When the conditions for running this DTC are met, the following conditions occur

1. The air-to-fuel ratio transitions from rich to lean.
2. The air-to-fuel ratio transitions from lean to rich, opposite the first air-to-fuel ratio transition.
3. The PCM captures the response time of the front and the rear HO2S when the air-to-fuel ratio transitions occur.
4. The PCM measures the time necessary for the rear HO2S voltage to cross a reference lean-to-rich threshold, and the time necessary for the front HO2S voltage to cross the same lean-to-rich threshold. The difference between the front HO2S time and the rear HO2S time indicates the oxygen storage capacity of the catalyst. If the PCM detects that this time difference is less than a predetermined value, DTC P0420 for bank 1 or DTC P0430 for bank 2 sets.

This diagnostic procedure supports the following DTCs

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

1. DTCs P0053, P0054, P0059, P0060, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0128, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0156, P0157, P0158, P0160, P0161, P0171, P0172, P0174, P0175, P0178, P0179, P0200, P0220, P0300, P0335, P0336, P0341, P0342, P0343, P0351-P0358, P0442, P0443, P0446, P0449, P0452, P0453, P0455, P0496, P0500, P0502, P0503, P0506, P0507, P1125, P1133, P1134, P1153, P1154, P1258, P1516, P2101, P2108, P2120, P2121, P2125, P2135 are not set.
2. The intake air temperature (IAT) is between -7°C and +85°C (20-185°F).
3. The barometric pressure (BARO) is greater than 74 kPa.
4. The engine coolant temperature (ECT) is more than 75°C-120°C (167°F-248°F).
5. The Closed Loop fuel control is enabled.
6. The HO2S 1 is less than 100 mv, while Decel Fuel Cutoff parameter is active.
7. The HO2S 2 is less than 100 mv for 1.6 seconds, while Decel Fuel Cutoff parameter is active.
8. The TP Indicated Angle parameter increases 3-20 percent after exiting DFCO.
9. The HO2S 1 is more than 600 mv after exiting DFCO.
10. The HO2S 2 is more than 230 mv after exiting DFCO.
11. This diagnostic attempts up to one test after exiting each valid DFCO period when the above conditions have been met. This diagnostic attempts up to 18 tests per drive cycle.

1. The PCM determines that the oxygen storage capability of the TWC has degraded to less than a calibrated threshold.
2. This diagnostic may conclude in only one test attempt. However this diagnostic may require as many as 108 test attempts, which would require 6 ignition cycles. Each test attempt occurs within 10 seconds.

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

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

1. The catalyst test may abort due to a change in the engine load. Do not change the engine load, ensure the AC is OFF, the coolant fan is not cycling, while a catalyst test is in progress.
2. Driving the vehicle under the conditions outlined in the Inspection/Maintenance (I/M) section can verify whether the fault is present.
3. These conditions may cause a catalytic converter to degrade. Inspect for the following conditions: An engine misfire High engine oil or high coolant consumption Retarded spark timing A weak or poor spark A lean fuel mixture A rich fuel mixture A damaged oxygen sensor or wiring harness If an intermittent condition cannot be duplicated, the information included in Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC was set.
4. The catalyst may have been temporarily contaminated with a chemical from a fuel additive, fuel contamination, or any of the above conditions.

If the condition is determined to be intermittent, refer to Testing for Intermittent Conditions and Poor Connections .

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

1. 5: A catalytic converter which has been discolored may be due to an engine running rich, lean or had a previous misfire. Verifying the fuel trim percentages may be of assistance in determining if such a condition exists.
2. 6: This steps inspects for conditions than can cause the TWC efficiency to appear degraded.

DTC P0420 or P0430 (With HP2)

System Description

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

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

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

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0335, P0336, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0464, P0496, P0500, P0502, P1106, P1107, P2610 are not set.
2. The diagnostic runs once with a 10 hour minimum between tests after a fail.
3. The start-up intake air temperature (IAT) is between 4-30°C (39-86°F).
4. The start-up engine coolant temperature (ECT) is less than 30°C (86°F).
5. The start-up IAT and ECT are within 8°C (15°F).
6. The barometric pressure (BARO) is greater than 74 kPa.
7. The ambient air temperature is between 2-32°C (36-90°F).
8. The engine run time minimum is 600 seconds.
9. The odometer displays greater than 10 miles.
10. The vehicle has traveled more than 3 miles this trip.
11. The ECT is more than 70°C (158°F).
12. The fuel level is between 15-85 percent.
13. The ignition is OFF.
14. One test occurs at ignition OFF after a cold start drive cycle and may require up to 45 minutes to complete. For the controller to report a fail, several tests must be completed with at least 17 hours between each test.

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

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

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

1. To help locate intermittent leaks, use the J 41413-200 Evaporative Emission System Tester (EEST) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light.
2. A condition may exist where a leak in the EVAP system only exists under a vacuum condition. This condition may be detected by using a scan tool PURGE/SEAL function to seal the EVAP system and create a vacuum. Then observe the FTP parameter for vacuum decay.
3. To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT .
4. For intermittent conditions, refer to «Testing for Intermittent Conditions and Poor Connections»(ref-197325-S02683201702005101100000) .

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

1. 3: Introducing smoke in 15 second intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
2. 5: This step verifies that repairs are complete and that no other condition is present.

DTC P0442

An ignition voltage is supplied directly to the evaporative emission (EVAP) canister purge solenoid valve. The EVAP canister purge solenoid valve is pulse width modulated (PWM). The scan tool displays the amount of ON time as a percentage. The control module monitors the status of the driver. The control module controls the EVAP canister purge solenoid valve ON time by grounding the control circuit via an internal switch called a driver. If the control module detects an incorrect voltage for the commanded state of the driver, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0443 Evaporative Emission (EVAP) Purge Solenoid Control Circuit

1. The engine speed is more than 400 RPM.
2. The system voltage is between 10-18 volts.
3. DTC P0443 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 conditions are present for a minimum of 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 numbers below refer to the step numbers on the diagnostic table.

1. 2: This step tests if the concern is active. The EVAP canister purge solenoid valve is PWM. You should hear a clicking sound when the EVAP canister purge solenoid valve is commanded to 50 percent. The clicking sound should stop when the EVAP canister purge solenoid valve is commanded to 0 percent. The rate at which the valve cycles should increase when the commanded state is increased, and decrease when the commanded state is decreased.
2. 5: This step verifies that the control module is providing ground to the EVAP canister purge solenoid valve.
3. 6: This step tests if a ground is constantly being applied to the EVAP canister purge solenoid valve.

DTC P0443

This DTC tests the Evaporative Emission (EVAP) System for a restricted or blocked EVAP vent path. The control module commands the EVAP canister purge solenoid valve Open and the EVAP canister vent solenoid valve Closed. This allows vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the EVAP canister purge solenoid valve Closed and the EVAP canister vent solenoid valve Open. The control module monitors the fuel tank pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 inches H2O in a calibrated time, this DTC sets.

The following table illustrates the relationship between the ON and OFF states, and the Open or Closed states of the EVAP canister purge and vent solenoid valves.

DTC P0446

This diagnostic procedure supports the following DTC

DTC P0446 Evaporative Emission (EVAP) Vent System Performance

1. DTCs P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0156, P0157, P0158, P0160, P0161, P0220, P0442, P0443, P0449, P0451, P0452, P0453, P0454, P0455, P0464, P0502, P0503, P1111, P1112, P1114, P1115, P1121, P1122, P1125, P2135 are not set.
2. The ignition voltage is between 10-18 volts.
3. The barometric pressure (BARO) is greater than 75 kPa.
4. The fuel level is between 15-85 percent.
5. The engine coolant temperature (ECT) is between 4-30°C (39-86°F).
6. The intake air temperature (IAT) is between 4-30°C (39-86°F).
7. The start up ECT and IAT are within 9°C (16°F) of each other.
8. DTC P0446 runs once per cold start when the above conditions are met.

1. The fuel tank pressure sensor is less than -12 inches H2O.
2. The above condition is present for more than 5 seconds.

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

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

1. When using the Evaporative Emission System Tester (EEST) to apply pressure, you can regulate the amount of pressure by activating the remote switch ON and OFF while observing pressure in the EVAP system using a scan tool. DO NOT use more than 5 inches H2O. More than 5 inches H2O applied to the EVAP system can cause the canister vent solenoid valve to temporarily remain in the closed position, which could lead to misdiagnosis in this procedure.
2. An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP canister vent solenoid valve inlet, or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill problem.
3. For intermittent conditions, refer to «Testing for Intermittent Conditions and Poor Connections»(ref-197325-S02683201702005101100000) .
4. An EVAP canister, vent hose, or vent solenoid valve that has restricted flow may cause this DTC to set. Using a purge solenoid valve command with a scan tool will allow vacuum to be applied to the system instead of pressure. With the EVAP canister vent solenoid valve open and the EVAP canister purge solenoid valve commanded to 100 percent, vacuum should not increase to more than 9 inches H2O.

DTC P0446

A battery positive is supplied to the evaporative emission (EVAP) canister vent solenoid valve. The control module grounds the EVAP canister vent solenoid valve control circuit to close the valve by means of an internal switch called a driver. The scan tool displays the commanded state of the EVAP canister vent solenoid valve as ON or OFF. The control module monitors the status of the driver. If the control module detects an incorrect voltage for the commanded state of the driver, this DTC sets.

The following table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP canister vent solenoid valve.

DTC P0449

This diagnostic procedure supports the following DTC

DTC P0449 Evaporative Emission (EVAP) vent Solenoid Control Circuit

1. The engine speed is more than 400 RPM.
2. The system voltage is between 10-18 volts.
3. DTC P0449 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 conditions are present for a minimum of 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 numbers below refer to the step numbers on the diagnostic table.

1. 2: Listen for a click when the valve operates. Verify that both the ON and the OFF states are commanded.
2. 5: This step verifies that the control module is providing ground to the EVAP canister vent solenoid valve.
3. 6: This step tests if the EVAP canister vent solenoid valve control circuit is grounded.

DTC P0449

The fuel tank pressure (FTP) sensor measures air pressure or vacuum in the evaporative emission (EVAP) system. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal voltage varies, depending on EVAP system pressure or vacuum. The controller uses this FTP signal to determine atmospheric pressure for use in the engine-off small leak test, P0442. Before using this signal as an atmospheric reference, it must first be re-zeroed. If the FTP signal is out of range during the re-zero procedure, this DTC will set.

This diagnostic procedure supports the following DTC

DTC P0451 Fuel Tank Pressure (FTP) Sensor Performance

1. DTC P0451 runs only when the engine-off natural vacuum small leak test, DTC P0442, executes.
2. The number of times this test runs can range from 0-2 per engine-off period. The length of the test can be up to 40 minutes.

This DTC will set if the controller is unable to re-zero the FTP sensor voltage within a calibrated range during the engine-off small leak test, P0442.

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 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 DTC with a scan tool.

1. A restriction in the EVAP canister or vent lines could prevent fuel vapor pressure from bleeding off fast enough. If the vent system cannot bleed off pressure fast enough, this code can set. When pressure is applied to the system and released, a properly operating system will return to the atmospheric pressure rapidly. By using a scan tool and the J 41413-200 Evaporative Emission System Tester (EEST), pressure can be applied to the system, then released, while monitoring the FTP sensor parameter to see that pressure can be released within 30 seconds.
2. An FTP sensor that is skewed or does not have a linear transition from low to high may cause this code to set. Scan tool output controls, snapshot, and plot functions can help detect erratic sensor response. To test the sensor signal under vacuum conditions, use the Quick Snapshot and the Purge/Seal functions to capture data while commanding purge to 20 percent, then plot the data to look for erratic sensor operation. A similar test can be done for the pressure side of the sensor operation by applying pressure with the J 41413-200 while taking a snapshot.
3. A full fuel tank may cause misdiagnosis.
4. When using the electronic emission system tester (EEST) to apply pressure, you can regulate the amount of pressure by activating the remote switch ON and OFF while observing pressure in the EVAP system using a scan tool.

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

1. 4: This step tests for the signal voltage that represents atmospheric pressure. Removing the fuel fill cap ensures a vented EVAP system. Record the value for possible use later in the diagnostic table.
2. 5: This step tests the accuracy of the FTP sensor by comparing the electrical signal value to the EEST mechanical gage value.
3. 8: A restricted EVAP system will not allow the nitrogen to flow freely through the system. A restriction will cause the FTP signal voltage parameter to decrease as the pressure builds.

DTC P0451

The fuel tank pressure (FTP) sensor measures the difference between the air pressure or vacuum in the evaporative emission (EVAP) system, and the outside air pressure. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal circuit voltage varies depending on EVAP system pressure or vacuum. If the FTP sensor signal voltage goes below a calibrated value, this DTC sets.

The following table illustrates the relationship between the FTP sensor signal voltage and the EVAP system pressure/vacuum.

DTC P0452

This diagnostic procedure supports the following DTC

DTC P0452 Fuel Tank Pressure (FTP) Sensor Circuit Low Voltage

1. The engine is running.
2. DTC P0452 runs continuously once the above condition is met.

1. The FTP sensor voltage is less than 0.1 volts.
2. All conditions are present 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. 5: This step tests for the proper operation of the circuit in the high voltage range.

DTC P0452

The fuel tank pressure (FTP) sensor measures the difference between the air pressure or vacuum in the evaporative emission (EVAP) system, and the outside air pressure. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal circuit voltage varies depending on EVAP system pressure or vacuum. If the FTP sensor signal voltage increases above a calibrated value, this DTC sets.

The following table illustrates the relationship between FTP sensor signal voltage and the EVAP system pressure/vacuum.

DTC P0453

This diagnostic procedure supports the following DTC

DTC P0453 Fuel Tank Pressure (FTP) Sensor Circuit High Voltage

1. The engine is running.
2. DTC P0453 runs continuously once the above condition is met.

1. The FTP sensor voltage is more than 4.9 volts.
2. All conditions are present 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. 2: If DTC P0641 or P0651 is set, the 5-volt reference circuit may be shorted to a voltage.

DTC P0453

The fuel tank pressure (FTP) sensor measures air pressure or vacuum in the evaporative emission (EVAP) system. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal voltage varies depending on EVAP system pressure or vacuum. The controller uses this FTP signal to determine atmospheric pressure for use in the engine OFF small leak test, P0442. This DTC will set if the control module detects an intermittent signal from the FTP that would prevent the engine-off small leak test, P0442, from running.

This diagnostic procedure supports the following DTC

DTC P0454 Fuel Tank Pressure (FTP) Sensor Circuit Intermittent

1. DTC P0454 runs only when the engine-off natural vacuum small leak test, P0442, executes.
2. This test can run once per engine-off period. The length of the test can be up to 40 minutes.

If, during the engine-off natural vacuum small leak test, P0442, the powertrain control module (PCM) detects an abrupt FTP signal change, other than a refueling event, this DTC will set.

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 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 DTC with a scan tool.

Scan tool output controls, snapshot, and plot functions can help detect erratic sensor response. To look at the sensor signal under vacuum conditions, use snapshot and the purge/seal function to capture data while commanding purge to 20 percent, then plot the data to look for non-linear sensor operation. A similar inspection can be done for the pressure side of the sensor range by applying pressure with J 41413-200 Evaporative Emission System Tester (EEST) while taking a snapshot. DO NOT exceed 5 inches H2O when applying pressure.

DTC P0454

The control module tests the evaporative emission (EVAP) system for a large leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the EVAP system vacuum level. When the conditions for running are met, the control module commands the EVAP canister purge solenoid valve open and the EVAP canister vent solenoid valve closed. This allows engine vacuum to enter the EVAP system. At a calibrated time, or vacuum level, the control module commands the EVAP canister purge solenoid valve closed, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum level. If the system is unable to achieve the calibrated vacuum level, or the vacuum level decreases too rapidly, this DTC sets.

The following table illustrates the relationship between the ON and OFF states, and the Open or Closed states of the EVAP canister purge and vent solenoid valves.

DTC P0455

This diagnostic procedure supports the following DTC

DTC P0455 Evaporative Emission (EVAP) System Large Leak Detected

1. Before the powertrain control module (PCM) can report DTC P0455 failed, DTC P0496 must run and pass.
2. DTCs P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0156, P0157, P0158, P0160, P0161, P0220, P0442, P0443, P0449, P0451, P0452, P0453, P0454, P0464, P0496, P0502, P0503, P1111, P1112, P1114, P1115, P1121, P1122, P1125, P2135 are not set.
3. The engine is running.
4. The ignition voltage is between 10-18 volts.
5. The barometric pressure (BARO) is more than 75 kPa.
6. The fuel level is between 15-85 percent.
7. The engine coolant temperature (ECT) is between 4-65°C (39-149°F).
8. The intake air temperature (IAT) is between 4-75°C (39-167°F).
9. The start-up ECT and IAT are within 9°C (16°F) of each other.
10. DTC P0455 runs once per cold start.

The EVAP system is not able to achieve or maintain vacuum during the diagnostic test.

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

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

1. To help locate intermittent leaks, use the J 41413-200 Evaporative Emission System Tester (EEST) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light. Introducing smoke in 15-second intervals will allow less pressure into the EVAP system. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
2. A temporary blockage in the EVAP canister purge solenoid valve, purge pipe, or EVAP canister could cause an intermittent condition. Inspect and repair any restriction in the EVAP system.
3. To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT .
4. Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
5. For intermittent conditions, refer to «Testing for Intermittent Conditions and Poor Connections»(ref-197325-S02683201702005101100000) .

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

1. 4: Introducing smoke in 15-second intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
2. 6: This step verifies proper operation of the FTP sensor.
3. 7: A normal operating FTP sensor should increase above 5 inches of H2O and stop between 6-7 inches of H2O.

DTC P0455

This DTC tests for undesired intake manifold vacuum flow to the Evaporative Emission (EVAP) System. The control module seals the EVAP system by commanding the EVAP canister purge solenoid valve Closed and the EVAP canister vent solenoid valve Closed. The control module monitors the fuel tank pressure (FTP) sensor to determine if a vacuum is being drawn on the EVAP system. If vacuum in the EVAP system is more than a predetermined value within a predetermined time, this DTC sets.

The following table illustrates the relationship between the ON and OFF states, and the Open or Closed states of the EVAP canister purge and vent solenoid valves.

DTC P0496

This diagnostic procedure supports the following DTC

DTC P0496 Evaporative Emission (EVAP) System Flow During Non-Purge

1. DTC P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0156, P0157, P0158, P0160, P0161, P0220, P0442, P0443, P0449, P0452, P0453, P0455, P0502, P0503, P1111, P1112, P1114, P1115, P1121, P1122, P1125, P2135 are not set.
2. The ignition voltage is between 10-18 volts.
3. The barometric pressure (BARO) is greater than 75 kPa.
4. The fuel level is between 15-85 percent.
5. The engine coolant temperature (ECT) is between 4-30°C (39-86°F).
6. The intake air temperature (IAT) is between 4-30°C (39-86°F).
7. The start up ECT and IAT are within 8°C (14°F) of each other.
8. DTC P0496 runs continuously once the above conditions are met.

1. A continuous open purge flow condition is detected during the diagnostic test.
2. The fuel tank pressure decreases to less than a calibrated value.

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

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

DTC P0496

The Electronic Throttle Control (ETC) System uses various inputs from the powertrain control module (PCM). This system uses the inputs to control the idle speed through serial data circuits to the throttle actuator control (TAC) module. The DC motor, which is located on the throttle body, activates the throttle plate. In order to decrease idle speed, the TAC module commands the throttle closed, reducing air flow into the engine, and the idle speed decreases. In order to increase the idle speed, the TAC module commands the throttle plate open, allowing more air in order to bypass the throttle plate. If the actual idle RPM does not match the desired idle RPM within a calibrated time, DTC P0506 sets.

This diagnostic procedure supports the following DTC

DTC P0506 Idle Speed Low

1. DTCs P0101-P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0125, P0171, P0172, P0174, P0175, P0200, P0220, P0300, P0440, P0442, P0443, P0496, P0500, P0502, P0503, P2135 are not set.
2. The engine is running for more than 60 seconds.
3. The engine coolant temperature (ECT) is more than 60°C (140°F).
4. The intake air temperature (IAT) is more than -10°C (+14°F).
5. The barometric pressure (BARO) is more than 65 kPa.
6. The system voltage is between 9-18 volts.
7. The vehicle speed is less than 1.7 km/h (1 mph).
8. The accelerator pedal position (APP) sensor is at 0 percent.
9. DTC P0506 runs continuously once the above conditions are met.

The PCM detects that the actual idle speed is 100 RPM less than the desired idle speed for 5 continuous 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: This test determines if the engine can achieve the commanded RPM.

DTC P0506 (With Throttle Actuator Control)

The electronic throttle control (ETC) system uses various inputs from the powertrain control module (PCM). This system uses these inputs to control the idle speed through serial data circuits to the throttle actuator control (TAC) module. The DC motor, which is located on the throttle body, activates the throttle plate. In order to decrease idle speed, the TAC module commands the throttle closed, reducing air flow into the engine, and the idle speed decreases. In order to increase the idle speed, the TAC module commands the throttle plate open, allowing more air in order to bypass the throttle plate. If the actual idle RPM does not match the desired idle RPM within a calibrated time, DTC P0507 sets.

This diagnostic procedure supports the following DTC

DTC P0507 Idle Speed High

1. DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0125, P0171, P0172, P0174, P0175, P0200, P0220, P0300, P0440, P0442, P0443, P0496, P0500, P0502, P0503, P2135 are not set.
2. The engine is running for more than 60 seconds.
3. The engine coolant temperature (ECT) is more than 60°C (140°F).
4. The intake air temperature (IAT) is more than -10°C (+14°F).
5. The barometric pressure (BARO) is more than 65 kPa.
6. The system voltage is between 9-18 volts.
7. The vehicle speed is less than 1.7 km/h (1 mph).
8. The accelerator pedal position (APP) sensor is at 0 percent.
9. DTC P0507 runs continuously once the above conditions are met.

The PCM detects that the actual idle speed is 200 RPM more than the desired idle speed for 5 continuous 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: This test determines if the engine can achieve the commanded RPM.

DTC P0507 (With Throttle Actuator Control)

Description

This diagnostic applies to internal microprocessor integrity conditions within the powertrain control module (PCM). This diagnostic also addresses whether or not the PCM is programmed.

This diagnostic procedure supports the following DTCs

1. DTC P0601 Control Module Read Only Memory (ROM)
2. DTC P0602 Control Module Not Programmed
3. DTC P0604 Control Module Random Access Memory (RAM)
4. DTC P0606 Control Module Internal Performance
5. DTC P2610 Control Module Ignition Off Timer Performance

DTC P0601

1. The ignition switch is in the Run or Crank position.
2. DTC P0601 runs continuously when the above condition is met.

DTC P0602

1. The ignition switch is in the ON position.
2. DTC P0602 runs continuously when the above condition is met.

DTC P0604

1. The ignition switch is in the Run or Crank position.
2. DTC P0604 runs continuously when the above condition is met.

DTC P0606

1. The ignition switch is in the Run or Crank position, or the key is being turned OFF.
2. DTC P0606 runs continuously when the above condition is met.

DTC P2610

1. The PCM is powered down.
2. DTC P2610 runs once every time the key is turned OFF.

The PCM detects an internal failure or incomplete programming for more than 5 seconds.

Action Taken When DTC P0601, P0602, P0604, and P0606 Sets

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

Action Taken When DTC P2610 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/DTCs P0601, P0602, P0604, P0606, and P2610

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: A DTC P0602 indicates the PCM is not programmed.

DTC P0601-P0607, P1600, P1621, P1627, P1680, P1681, P1683, or P2610

The powertrain control module (PCM) provides 5 volts to the following sensors

1. The engine oil pressure (EOP) sensor
2. The manifold absolute pressure (MAP) sensor

These 5-volt reference circuits are independent of each other outside the PCM, but are bussed together inside the PCM. Therefore a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The PCM monitors the voltage on the 5-volt reference circuit. If the PCM detects that the voltage is out of tolerance, DTC P0641 sets.

This diagnostic procedure supports the following DTC

DTC P0641 5-Volt Reference 1 Circuit

1. The engine is running.
2. DTC P0641 runs continuously once the above condition is met.

The PCM detects a voltage out of tolerance condition on the 5-volt reference circuit 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. 9: A short to voltage on the signal circuit of the manifold absolute pressure (MAP) sensor will backfeed through the sensor into the 5-volt reference circuit and set this DTC.

DTC P0641

The malfunction indicator lamp (MIL) is located on the instrument panel cluster (IPC). The MIL informs the driver that an emission system fault has occurred and that the engine control system requires service. The control module monitors the MIL control circuit for conditions that are incorrect for the commanded state of the MIL. For example, a failure condition exists if the control module detects low voltage when the MIL is commanded OFF, or high voltage when the MIL is commanded ON. If the control module detects an improper voltage on the MIL control circuit, DTC P0650 will set.

This diagnostic procedure supports the following DTC

DTC P0650 Malfunction Indicator Lamp (MIL) Control Circuit

1. The engine speed is more than 400 RPM.
2. The ignition voltage is between 6-18 volts.
3. DTC P0650 runs continuously when the above conditions are met.

The control module detects that the commanded state of the MIL driver and the actual state of the control circuit do not match for more than 5 seconds.

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. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
3. Clear the MIL and the DTC with a scan tool.

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

1. 6: This step tests for a short to ground in the MIL control circuit. With the powertrain control module (PCM) disconnected and the ignition ON, the MIL should be OFF.
2. 7: This step tests for a short to voltage on the MIL control circuit. With the fuse removed, there should be no voltage on the MIL control circuit.

DTC P0650

The powertrain control module (PCM) provides 5 volts to the following sensors

1. The air conditioning (A/C) pressure sensor
2. The fuel tank pressure (FTP) sensor

These 5-volt reference circuits are independent of each other outside the PCM, but are bussed together inside the PCM. Therefore a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The PCM monitors the voltage on the 5-volt reference circuit. If the PCM detects that the voltage is out of tolerance, DTC P0651 sets.

This diagnostic procedure supports the following DTC

DTC P0651 5-Volt Reference 2 Circuit

1. The engine is running.
2. DTC P0651 runs continuously when the above condition is met.

The PCM detects a voltage out of tolerance condition on the 5-volt reference circuit 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. 9: A short to voltage on the signal circuit of the FTP sensor will backfeed through the sensor into the 5-volt reference circuit and set this DTC.

DTC P0651

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

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

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

If the PCM detects a MAP sensor signal voltage that is intermittently high, DTC P1106 sets.

This diagnostic procedure supports the following DTC

DTC P1106 Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent High Voltage

1. DTCs P0068, P0120, P0220, P2135 are not set.
2. The engine is running.
3. The throttle angle is less than 0.4 percent when the engine speed is less than 1,200 RPM. OR
4. The throttle angle is less than 20 percent when the engine speed is more than 1,200 RPM.
5. DTC P1106 runs continuously when the above conditions are met.

The PCM detects that the MAP sensor voltage is intermittently more than 4.9 volts for a calibrated amount of time.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

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

1. 3: This step attempts to pinpoint the location of the intermittent fault.

DTC P1106

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

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

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

If the PCM detects a MAP sensor signal voltage that is intermittently low, DTC P1107 sets.

This diagnostic procedure supports the following DTC

DTC P1107 Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent Low Voltage

1. The ignition is ON.
2. DTCs P0068, P0120, P0220, P0641, P0651, P2135 are not set.
3. The throttle angle is more than 0 percent when the engine speed is less than 800 RPM. OR
4. The throttle angle is more than 12.5 percent when the engine speed is more than 800 RPM.
5. DTC P1107 runs continuously when the above conditions are met.

The PCM detects that the MAP sensor voltage is intermittently less than 0.055 volt for a calibrated amount of time.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

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

1. 3: This step attempts to pinpoint the location of the intermittent fault.

DTC P1107

The intake air temperature (IAT) sensor is a variable resistor. The IAT sensor has a signal circuit and a low reference circuit. The IAT sensor measures the temperature of the air entering the engine. The powertrain control module (PCM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit. When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance decreases. With high sensor resistance, the PCM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the IAT signal circuit. If the PCM detects an intermittent high IAT signal voltage, indicating a low temperature, DTC P1111 sets.

This diagnostic procedure supports the following DTC

DTC P1111 Intake Air Temperature (IAT) Sensor Circuit Intermittent High Voltage

1. DTCs P0101, P0102, P0103, P0113 are not set.
2. The engine run time is more than 120 seconds.
3. The ECT sensor parameter is more than 60°C (140°F).
4. The vehicle speed is less than 11 km/h (7 mph).
5. The mass air flow is less than 15 g/s.
6. DTC P1111 runs continuously when the above conditions are met.

The PCM detects that the IAT sensor parameter is less than -38°C (-36°F) intermittently for a calibrated amount of time.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

1. An IAT sensor or PCM which is intermittently shorted, open, or skewed is possible, yet very unlikely.
2. A skewed sensor could result in poor driveability conditions.
3. If an intermittent condition is suspected, refer to «Intermittent Conditions»(ref-197378-S14557473772005101100000) .

DTC P1111

The intake air temperature (IAT) sensor is a variable resistor. The IAT sensor has a signal circuit and a low reference circuit. The IAT sensor measures the temperature of the air entering the engine. The powertrain control module (PCM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit. When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance decreases. With high sensor resistance, the PCM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the IAT signal circuit. If the PCM detects an intermittent low IAT signal voltage, indicating a high temperature, DTC P1112 sets.

This diagnostic procedure supports the following DTC

DTC P1112 Intake Air Temperature (IAT) Sensor Circuit Intermittent Low Voltage

1. DTCs P0112 is not set.
2. The engine run time is more than 45 seconds.
3. The vehicle speed is more than 40 km/h (25 mph).
4. The ECT sensor parameter is less than 125°C (257°F).
5. DTC P1112 runs continuously when the above conditions are met.

The PCM detects that the IAT sensor parameter is more than 128°C (262°F) intermittently for a calibrated amount of time.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

1. An IAT sensor or PCM which is intermittently shorted, open, or skewed is possible, yet very unlikely.
2. A skewed sensor could result in poor driveability conditions.
3. If an intermittent condition is suspected, refer to «Intermittent Conditions»(ref-197378-S14557473772005101100000) .

DTC P1112

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 P1114 sets.

This diagnostic procedure supports the following DTC

DTC P1114 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent Low Voltage

1. The engine run time is more than 10 seconds. OR The engine run time is less than 10 seconds when the intake air temperature (IAT) is less than 50°C (122°F).
2. DTC P1114 runs continuously when the above condition is met.

The PCM detects that the ECT sensor parameter is more than 138°C (280°F) intermittently for a calibrated amount of time.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

1. An ECT sensor or PCM which is intermittently shorted, open, or skewed is possible, but very unlikely
2. An intermittent short to ground in the ECT sensor signal circuit could result in a DTC P1114.
3. Use the Temperature vs. Resistance Value scale to test the coolant sensor at various temperature levels to evaluate the possibility of a skewed sensor. A skewed sensor could result in poor driveability conditions. Refer to «Temperature vs Resistance»(ref-197340-S13610010342005101100000) .
4. For an intermittent condition, refer to «Intermittent Conditions»(ref-197378-S14557473772005101100000) .

DTC P1114

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 high signal voltage, which is a low temperature indication, DTC P1115 sets.

This diagnostic procedure supports the following DTC

DTC P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage

1. The engine run time is more than 60 seconds. OR
2. The engine run time is less than 60 seconds when the intake air temperature (IAT) is more than 0°C (32°F).
3. DTC P1115 runs continuously when the above condition is met.

The PCM detects that the ECT sensor parameter is less than -38°C (-36°F) intermittently for a calibrated amount of time.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

1. An ECT sensor or PCM which is intermittently shorted, open, or skewed is possible, but very unlikely.
2. An intermittent open or a short to voltage in the ECT sensor signal circuit could result in DTC P1115 setting. Refer to «Intermittent Conditions»(ref-197378-S14557473772005101100000) .
3. Use the Temperature vs. Resistance Value table to test the coolant sensor at various temperature levels to evaluate the possibility of a skewed sensor. A skewed sensor could result in poor driveability conditions. Refer to «Temperature vs Resistance»(ref-197340-S13610010342005101100000) .

DTC P1115

The accelerator pedal position (APP) sensor 1 and the APP sensor 2 are potentiometer type sensors, each with the following circuits

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

The control module provides the APP sensors with a 5-volt reference circuit and a low reference circuit. The APP sensors then provide the control module signal voltages proportional to pedal movement. The APP sensor 1 signal voltage is low at rest and increases as the pedal is depressed. The APP sensor 2 signal voltage is low at rest and increases as the pedal is depressed. When the control module detects that the APP sensor 1 and the APP sensor 2 signal circuits are out of correlation with each other, DTC P1125 sets.

This diagnostic procedure supports the following DTC

DTC P1125 Accelerator Pedal Position (APP) System

1. DTC P2108 or U0107 is not set.
2. The ignition is in the Crank or Run position.
3. The ignition voltage is more than 5.23 volts.
4. DTC P1125 runs continuously once the above conditions are met.

1. Both APP sensors are out of range. OR
2. Both APP sensors disagree. OR
3. One APP sensor is out of range and the other APP sensor disagrees.
4. One of the above conditions is present for more than 0.019 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 P1125

See also:
• Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 2
• Special Tools
• Engine Controls Connector End Views
• Powertrain Control Module (PCM) Connector End Views
• Service Programming System (SPS)
• Engine Oil Pressure Sensor and/or Switch Replacement