P0454

DTC P0454

DTC DESCRIPTOR

DTC P0454
Fuel Tank Pressure (FTP) Sensor Intermittent

DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection






TYPICAL SCAN TOOL DATA

FTP Sensor Voltage:

CIRCUIT/SYSTEM DESCRIPTION
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 also uses this FTP signal to determine atmospheric pressure for use in the engine-off small leak test, DTC P0442. Before using this signal as an atmospheric reference it must first be re-zeroed.

CONDITIONS FOR RUNNING THE DTC
- DTC P0454 runs only when the engine-off natural vacuum small leak test, DTC P0442, executes.
- This test can run once per engine-off period. The length of the test can be up to 10 minutes.
- A refueling event is not detected.

CONDITIONS FOR SETTING THE DTC
If, during the engine-off natural vacuum small leak test, DTC P0442, the engine control module (ECM), detects an abrupt FTP signal change other than a refueling event, this DTC will set. An abrupt change is defined as a change of 1 inch H2O in the span of 1 second.

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

DIAGNOSTIC AIDS
- This diagnostic is designed to detect an unexpected abrupt voltage signal change from the FTP.
- 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 30 percent, and then plot the data to look for erratic sensor operation. A similar inspection can be done for the pressure side of the sensor range by applying pressure with the J 41413-200 while taking a snapshot.
- Ensure that the reference port on the FTP sensor is unobstructed.

CIRCUIT/SYSTEM VERIFICATION
1. Start the engine with the J 41413-200 connected to the fuel filler neck.

IMPORTANT: Refer to the J 41413-200 operation manual for detailed instructions.

2. Allow the engine to idle.
3. Use the Purge/Seal function to seal the system with a scan tool.
4. Command the EVAP canister purge solenoid valve to 30 percent.
5. Observe the vacuum/pressure gage on the J 41413-200 and the FTP parameter on the scan tool.
6. Allow the vacuum to increase on the gage of the J 41413-200 until it reaches approximately 16 inches H2O, or until the vacuum reached the abort limit on the scan tool.
7. Use the Purge/Seal function to seal the system with a scan tool.
8. If the difference between the FTP parameter on a scan tool and the vacuum/pressure gage on the J 41413-200 is more than 1 inch H2O, replace the FTP sensor.
9. If the Fuel Tank Pressure Sensor parameter on a scan tool display is less than 3.2 volts, replace the FTP sensor.

CIRCUIT/SYSTEM TESTING
1. If DTCs P0452, P0453, or P0641 are set, repair those first.
2. With a scan tool, command the EVAP canister vent solenoid valve closed.
3. Command the purge solenoid to 30 percent.
4. Observe the FTP sensor voltage parameter as the vacuum increased to the abort limit.
5. The voltage should scale smoothly.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Fuel Tank Pressure Sensor Replacement
- Control Module References for ECM replacement, setup, and programming Verification Tests