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P0454




DTC P0451-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 P0452
- Fuel Tank Pressure (FTP) Sensor Circuit Low Voltage

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

DTC P0454
- Fuel Tank Pressure (FTP) Sensor Intermittent

Diagnostic Fault Information





Typical Scan Tool Data





Circuit/System Description

The fuel tank pressure (FTP) sensor measures air pressure or vacuum in the evaporative emission (EVAP) system. The engine control module (ECM) supplies a 5-volt reference circuit and a low reference circuit to the FTP sensor. The FTP sensor signal voltage varies depending on EVAP system pressure or vacuum. The ECM 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

P0451
* DTC P0451 runs only when the engine-off natural vacuum small leak test, DTC P0442, executes.
* 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 10 minutes.

P0452 and P0453

DTCs P0452 and P0453 run continuously when the ignition is ON.

P0454
* 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

P0451

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, DTC P0442.

P0452

The FTP sensor voltage is less than 0.1 volt for more than 5 seconds.

P0453

The FTP sensor voltage is more than 4.9 volts for more than 5 seconds.

P0454

If, during the engine-off natural vacuum small leak test, DTC P0442, the 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

P0451 and P0454
* The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
* The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Freeze Frame/Failure Records.

P0452 and P0453
* The ECM illuminates the MIL on the second consecutive ignition cycle that the diagnostic runs and fails.
* The ECM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the ECM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the ECM records the operating conditions at the time of the failure. The ECM writes the operating conditions to the Freeze Frame and updates the 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

P0451
* 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, the re-zero procedure may not complete successfully, which could cause this code to set. By using the Purge Solenoid command on a scan tool, vacuum can 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, the vacuum should not increase to more than 9 inches H2O.
* Ensure that the reference port on the FTP sensor is unobstructed.

P0454
* 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, 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.

Reference Information
Schematic Reference

Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
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)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information
Special Tools

J 41413-200 Evaporative Emission System Tester (EEST)

Circuit/System Verification

1. Remove the fuel cap.
2. Turn ON the ignition, with the engine OFF.
3. Observe the Fuel Tank Pressure Sensor parameter with a scan tool.
4. The FTP Sensor parameter should be 1.5 volts.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the FTP sensor.
2. Ignition OFF, ensure that the ECM completely powers down and test for less than 5 ohms between the low reference circuit terminal A and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the control module.

3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal C and ground.

• If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the control module.
• If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the control module.

4. Verify the scan tool FTP sensor parameter is less than 0.2 volt.

• If greater than the specified range, test the signal circuit terminal B for a short to voltage. If the circuit tests normal, replace the control module.

5. Install a 3A fused jumper wire at the signal circuit terminal B and the 5-volt reference circuit terminal C. Verify the scan tool FTP sensor voltage parameter is greater than 4.7 volts.

• If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the control module.

6. If all circuits test normal, replace the FTP sensor.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Fuel Tank Pressure Sensor Replacement (Fuel Tank Pressure Sensor Replacement)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming

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