For 1990-2009 cars

### 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. This DTC will set if the control module detects an intermittent signal from the FTP that would prevent the engine-off small leak test, DTC P0442, from running.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0454 Fuel Tank Pressure (FTP) Sensor Circuit Intermittent

### Conditions for Running the DTC

• | DTC P0454 runs only when the engine-off natural vacuum small leak test, 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, 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 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 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 Evaporative Emissions System Tester (EEST) while taking a snapshot.

• | Ensure that the reference port on the FTP sensor is unobstructed.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Are DTCs P0452, P0453 or P0651 also set? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | Go to Step 3
3 | Inspect the sensor signal under vacuum using the following procedure:

1. With a scan tool, command the evaporative emission (EVAP) canister vent solenoid valve closed.
2. Command the purge solenoid to 30 percent.
3. Observe the fuel tank pressure (FTP) sensor voltage parameter as the vacuum increased to the abort limit.

Did you observe an erratic voltage signal?

--

Go to Step 4

Go to Step 5

4 | Inspect for an intermittent a for a poor connection at the FTP sensor. Refer to Testing for Intermittent Conditions and Poor Connections . Did you find and correct the condition? | -- | Go to Step 7 | Go to Step 6
5 | Important: Do not exceed the specified value. Exceeding the specified value may produce incorrect test results. Inspect the sensor signal under pressure using the following procedure:

1. Connect the J 41413-200 Evaporative Emissions System Tester (EEST) to the fuel fill pipe.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, command the EVAP canister vent solenoid valve closed.
4. Turn the nitrogen/smoke valve on the J 41413-200 control panel to NITROGEN.
5. Use the remote switch to pressurize the EVAP system to the specified value.
6. With a scan tool, observe the FTP sensor in volts.
7. With a scan tool, command the EVAP canister vent solenoid valve open.

Did you observe an erratic voltage signal?

5 in H2O

Go to Step 4

Go to Diagnostic Aids

6 | Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 7 | --
7 |

1. Turn OFF the ignition.
2. Remove the fuel filler cap.
3. Turn ON the ignition, with the engine OFF.

Is the FTP sensor parameter within the specified value?

-1 to +1 in H2O

Go to Step 8

Go to Diagnostic Aids

8 | With a scan tool, observe the Capture Info. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK