For 1990-2009 cars

### Circuit Description

The fuel level sensor changes resistance based on fuel level. The fuel level sensor has a signal circuit and a ground circuit. The engine control module (ECM) applies 5 volts on the signal circuit to the sensor. The ECM monitors the changes in this voltage caused by changes in the resistance of the sensor in order to determine fuel level.

When the fuel tank is full, the sensor resistance is low, and the ECM signal voltage is high. When the fuel tank is empty, the sensor resistance is high, and the signal voltage is low.

The ECM uses inputs from the fuel level sensor in order to calculate the total fuel percentage remaining in the fuel tank. The ECM uses the fuel level information for the evaporative emission (EVAP) and misfire diagnostics. The fuel level information is sent to the instrument panel cluster (IPC).

If the ECM detects that the fuel level sensor signal changes more than a calibrated amount within a certain time, this DTC sets.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0464 Fuel Level Circuit Intermittent

### Conditions for Running the DTC

• | DTCs P0107, P0108, P0112, P0113, P0122, P0123, and P0502 are not set.

• | The engine is running.

• | This diagnostic will be delayed for 5 seconds if one or more of the following occurs:

- | The change in manifold absolute pressure (MAP) sensor is more than 10 kPa.

- | The change in engine speed is more than 50 RPM.

- | The change in throttle position (TP) sensor is less than 2 percent.

- | The intake air temperature (IAT) sensor is more than -10°C (50°F).

### Conditions for Setting the DTC

The ECM detects that the fuel level changes more than 3.9 percent for 7.5 seconds.

### Action Taken When the DTC Sets

• | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

• | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

• | The fuel gage defaults to empty.

### 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 the DTC with a scan tool.

### Test Description

The number below refers to the step number on the diagnostic table.

1. This step attempts to determine if the intermittent fault is a connector.

1. This step attempts to determine the location of the intermittent fault.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Instrument Cluster Schematics or Connector End View Reference: Displays and Gages Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Start the engine.
2. Observe the DTC Information with a scan tool.

Are DTCs P0461, P0462, and P0463 also set?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

3 | Observe the Fuel Level Sensor voltage parameter with a scan tool while moving the fuel level sensor connector and the engine control module (ECM) connector. Refer to Inducing Intermittent Fault Conditions . Does the scan tool indicate an abrupt change in value? | Go to Step 5 | Go to Step 4
4 | Observe the fuel level sensor voltage with a scan tool while moving the wiring harness between the fuel level sensor connector and the ECM. Refer to Inducing Intermittent Fault Conditions . Does the scan tool indicate an abrupt change in value? | Go to Step 6 | Go to Step 7
5 | Repair the connector terminal, as necessary. Refer to Connector Repairs . Did you complete the repair? | Go to Step 7 | --
6 | Repair the harness/wiring, as necessary. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 7 | --
7 |

1. Clear the DTCs with a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 8

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