P0454

DTC P0451 or P0454 (LUW)

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 provide an overview of each diagnostic category.

DTC Descriptors

DTC P0451
- Fuel Tank Pressure Sensor Performance

DTC P0454
- Fuel Tank Pressure Sensor Circuit Intermittent

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 sensor is used for EVAP system diagnostics. The fuel tank pressure sensor is a transducer that varies resistance according to changes in fuel tank pressure. The engine control module (ECM) monitors the fuel tank pressure sensor signal in order to detect vacuum decay and excess vacuum during the EVAP system diagnostic tests.

Conditions for Running the DTC

P0451

* This diagnostic runs when the engine off natural vacuum small leak test, DTC P0442, is in progress.

* This diagnostic can be tested 0-2 times during the engine off period.

P0454

* This diagnostic runs when the engine off natural vacuum small leak test, DTC 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 fuel tank pressure sensor voltage within a calibrated range. The length of the test can be up to 10 min.

P0454

The ECM detects an abrupt change in the fuel tank pressure sensor voltage, other than a refueling event. The length of the test can be up to 10 min.

Action Taken When the DTC Sets

DTCs P0451 and P0454 are Type A DTCs.

Conditions for Clearing the DTC

DTCs 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 fuel tank pressure sensor is not restricted.

* A resistance in the circuits of the fuel tank pressure 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 Fuel Pump and Level Sensor Assembly

Description and Operation

Evaporative Emission Control System Description Description and Operation

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 Control Module References for scan tool information

Special Tools

* GE 41414-A - Evaporative Emissions System Tester

* GE 41415-50 - Fuel Tank Cap Adapter

* J 41413-300 - EVAP Cap And Plug Kit

For equivalent regional tools, refer to Special Tools Tools and Equipment.

Circuit/System Testing

1. If DTC P0454 is set inspect for an intermittent and for a poor connection at the B150 Fuel Tank Pressure Sensor and the K20 Engine Control Module.

2. Remove the fuel fill cap. Connect the GE 41415-50 - Fuel Tank Cap Adapter to the fuel tank filler neck.

3. Connect the GE 41414-A - Evaporative Emissions System Tester to the GE 41415-50 - Fuel Tank Cap Adapter.

4. Pressurize the EVAP system with nitrogen to 1 kPa (0.14 psi). Compare the Fuel Tank Pressure Sensor parameter with a scan tool to the GE 41414-A - Evaporative Emissions System Tester pressure/vacuum gauge. The scan tool fuel tank pressure sensor parameter should be within 1 kPa (0.14 psi) of the pressure/vacuum gauge.

• If not within the specified range, replace the B150 Fuel Tank Pressure Sensor.

5. Command the EVAP purge solenoid valve OPEN with a scan tool. Verify the scan tool Fuel Tank Pressure Sensor parameter decreases quickly to 0 kPa (0 psi).

• If the pressure does not decrease quickly, inspect the EVAP vent system for a restriction. If the EVAP vent system tests normal replace the B150 Fuel Tank Pressure Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.