For 1990-2009 cars

### 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.

### Circuit/System Description

The fuel level sensor changes resistance in response to the fuel level. The engine control module (ECM) monitors the signal circuit of the fuel level sensor in order to determine fuel level. When the fuel tank is full, the sensor resistance is high and the ECM senses a high signal voltage. When the fuel tank is empty, the sensor resistance is low and the ECM senses a low signal voltage. The ECM uses the signal circuit of the fuel level sensor in order to calculate the total remaining fuel percentage in the tank. The ECM sends the fuel level percentage via the class 2 serial data circuit to the instrument panel cluster (IPC) in order to supply the fuel gage display. The fuel level information is also used for misfire and evaporative emission (EVAP) diagnosis.

This diagnosis tests the fuel level sensor signal for an intermittent failure. If the fuel level change is detected, the action of filling the fuel can disable the engine DTC P0442 of closing the permanent vacuum slight leakage test. Before disabling the DTC P0442, perform the test of filling the fuel action in order to ensure the fuel is refilled. If the action of filling the fuel is ensured, it indicates this test is passed. Otherwise, set a DTC P0464 to indicate an intermittent failure.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0464 Fuel Level Sensor Circuit Intermittent Failure

### Conditions for Running the DTC

• | The ignition switch is OFF.

• | DTC P0442 is running.

### Conditions for Setting the DTC

• | In the engine OFF test, the fuel level change is greater than 15 percent.

• | The above condition is present and continues for more than 30 seconds.

### Action Taken When the DTC Sets

• | Disable the DTC P0442.

• | DTC P0464 is a type A DTC.

### Conditions for Clearing the DTC

DTC P0464 is a type A DTC.

### Diagnostic Aids

Use the Freeze Frame/Failure Records data in order to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records data may help in determining the number of miles since the DTC set. The Fail Counter and Pass Counter can also help in determining the number of ignition cycles that the diagnostic test reported a pass and/or fail. Operate the vehicle within the same freeze frame conditions, including those for RPM, for engine load, for vehicle speed, for temperature, and for others.

• | Refer to Testing for Intermittent Conditions and Poor Connections

• | If a DTC is set under non-filling the fuel condition, refer to Fuel Gage Inaccurate or Inoperative