GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2007 🢒 VUE - AWD 🢒 DTC 🢒 DTC P0451 or P0454

Diagnostic Instructions
    •  Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    •  Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  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

Typical Scan Tool Data

FTP Sensor

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: Engine idling in Closed Loop.

Parameter Normal Range: 0.2 V-4.8 V

5-Volt Reference Voltage

0 V

0 V

5 V

FTP Sensor Signal

0 V

0 V

5 V

Low Reference

--

4.2 V

--

Circuit/System Description

The evaporative emission (EVAP) system is used to store fuel vapors in order to reduce the amount of fuel vapors into the atmosphere. The fuel tank pressure (FTP) sensor is only used for EVAP system diagnostics. The FTP sensor is a transducer that varies resistance according to changes in the fuel tank pressure. The powertrain control module (PCM) monitors the FTP sensor signal in order to detect vacuum decay and excess vacuum during the EVAP system diagnostic test. The PCM supplies a 5-volt reference and a low reference circuit to the FTP sensor.

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

FTP Sensor Signal Voltage

Fuel Tank Pressure

High, Approximately 1.5 Volts or More

Negative Pressure/Vacuum

Low, Approximately 1.5 Volts or Less

Positive Pressure

Conditions for Running the DTC

P0451

    • Before the PCM can report DTC P0451 failed, DTCs P0443, P0452, and P0453 must run and pass.
    • The engine is running.
    • The ambient air temperature is greater than 4°C (40°F).
    • The vehicle speed is greater than 45 km/h (28 mph).
    • The FTP sensor voltage is greater than 0.3 volt.
    • The purge flow fluctuation is greater than 0.05 kg/h.
    • DTC P0451 runs continuously once the above conditions are met.

P0454

    • The ignition is ON.
    • The ignition voltage is between 9-16 volts.
    • DTC P0454 runs continuously once the above conditions are met.

Conditions for Setting the DTC

P0451

The PCM detects the FTP sensor voltage fluctuates less than 0.01 volt for greater than 5 seconds.

P0454

The PCM detects an abrupt change in the FTP sensor voltage for greater than 10 seconds.

Action Taken When the DTC Sets

DTC P0451 and P0454 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTC P0451 and P0454 are Type B DTCs.

Diagnostic Aids

If a shared 5-volt reference circuit is shorted to ground or shorted to a voltage, other 5-volt reference circuits may be affected.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Powertrain Control Module Connector End Views
    •  Engine Controls Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Special Tools Required

    • J 41413-200 Evaporative Emissions System Tester (EEST)
    • GE-41415-50 Fuel Tank Cap Adapter

Circuit/System Testing
  1. If DTC P0454 is set, inspect for an intermittent and for a poor connection at the FTP sensor.
  2. Ignition OFF, remove the fuel tank filler cap.
  3. Connect the GE-41415-50 to the fuel fill pipe. Connect the J 41413-200 to the J 41415-40 . Install the fuel tank filler cap to the GE-41415-50 .
  4. Ignition ON, engine OFF, seal the EVAP system with a scan tool.

    5. Important: DO NOT exceed the specified value in this step. Exceeding the specified value may produce incorrect test results.

  5. Turn the nitrogen/smoke valve on the J 41413-200 to nitrogen. Use the remote switch to pressurize the fuel tank with nitrogen to 10 inch H20.
  6. Compare the scan tool FTP sensor parameter to the J 41413-200 pressure/vacuum gage. The scan tool FTP sensor parameter should be within 1 inch H20 of the pressure/vacuum gage.
    7. ⇒If not within the specified range, replace the FTP sensor.
  7. With a scan tool command the vent solenoid valve OPEN. The scan tool FTP sensor parameter should read 0 inch H20.
    8. ⇒If not within the specified range, replace the FTP sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Fuel Tank Pressure Sensor Replacement
    •  Powertrain Control Module Replacement for PCM replacement, setup, and programming