P0454
DTC P0451 or P0454
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0451
- Fuel Tank Pressure (FTP) Sensor Performance
DTC P0454
- Fuel Tank Pressure (FTP) Sensor Intermittent
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The evaporative emission (EVAP) system stores fuel vapors in order to reduce the amount of fuel vapors into the atmosphere. The fuel tank pressure (FTP) sensor is used for EVAP system diagnostics. The FTP sensor is a transducer that varies resistance according to changes in fuel tank pressure. The engine control module (ECM) monitors the FTP sensor signal in order to detect vacuum decay and excess vacuum during the EVAP system diagnostic tests.
The following table illustrates the relationship between FTP sensor signal voltage and the EVAP system pressure/vacuum.
Conditions for Running the DTC
P0451
* This diagnostic runs when the engine-off natural vacuum small leak test, P0442, is in progress.
* This diagnostic can be tested 2 times during the engine-off period.
P0454
* This diagnostic runs when the engine-off natural vacuum small leak test, P0442, is in progress.
* This diagnostic can be tested 1 time during the engine-off period.
* The ECM does not detect a refueling event.
Conditions for Setting the DTC
P0451
DTC P0451 will set if the controller is unable to re-zero the FTP sensor voltage within a calibrated range. The length of the test can be up to 10 minutes.
P0454
The ECM detects an abrupt change in the FTP sensor voltage, other than a refueling event. The length of the test can be up to 10 minutes.
Action Taken When the DTC Sets
DTC P0451 and P0454 are Type A DTCs.
Conditions for Clearing the MIL/DTC
DTC P0451 and P0454 are Type A DTCs.
Diagnostic Aids
* A restriction in the EVAP canister or vent lines could prevent fuel vapor pressure from decreasing fast enough. If the pressure does not decrease fast enough, the re-zero procedure may not complete successfully, which could cause DTC P0451 to set.
* Verify that the reference port on the FTP sensor is not restricted.
* A resistance in the circuits of the FTP sensor may cause DTC P0451 to set.
Reference Information
Schematic Reference
Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Evaporative Emission Control System Description (Evaporative Emission Control System Description)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Special Tools
* J 41413-200 Evaporative Emissions System Tester (EEST)
* GE-41415-50 Fuel Tank Cap Adapter
* J 41413-300 EVAP Cap and Plug Kit
Circuit/System Testing
1. If DTC P0454 is set Inspect for an intermittent and for a poor connection at the FTP sensor and the engine control module (ECM).
2. Remove the fuel fill cap. Connect the GE-41415-50 to the fuel tank filler neck. Connect the J 41413-200 to the GE-41415-50.
3. Pressurize the EVAP system with nitrogen to 5 inches H2O. Compare the Fuel Tank Pressure Sensor parameter with a scan tool to the J 41413-200 pressure/vacuum gauge. The scan tool FTP sensor parameter should be within 1 inch H2O of the pressure/vacuum gauge.
• If not within the specified range, replace the FTP sensor.
4. Command the EVAP purge solenoid valve OPEN with a scan tool. Verify the scan tool FTP senor parameter decreases quickly to 0 inch H2O.
• If the pressure does not decrease quickly, inspect the EVAP vent system for a restriction. If the EVAP vent system tests normal replace the FTP sensor.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Fuel Tank Pressure Sensor Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming