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).

This diagnostic tests for a stuck fuel level sensor signal. If the fuel level signal appears to be stuck, based on a lack of signal variation expected during normal operation, this DTC sets.

### DTC Descriptors

This diagnostic procedure supports the following DTC:

DTC P0461 Fuel Level Sensor Circuit Performance

### Conditions for Running the DTC

• | DTCs P0462, P0463, and P0502 are not set.

• | The engine is running.

• | DTC P0461 runs continuously once the above conditions are met.

### Conditions for Setting the DTC

The ECM does not detect a decrease in fuel level over a distance of 250 km (155 miles).

### 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 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

Check for the following conditions:

A poor connection or damaged harness--Inspect ECM harness connectors for the following:

• | Backed out terminals

• | Improper mating

• | Broken locks

• | Poor wire to terminal connections

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This step determines if the fault is present.

2. This step determines if the fuel level sensor signal and ground circuits are OK.

Step | Action | Value | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Instrument Cluster Schematics Connector End View Reference: Component Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Important: If DTCs P0462 or P0463 are also set, diagnose those DTCs first. Refer to DTC P0462 or DTC P0463 .

1. Turn OFF the ignition.
2. Disconnect the fuel level sender through the access panel under the rear seat.
3. Jumper the fuel level sensor signal circuit to a known good ground.
4. Turn ON the ignition, with the engine OFF.
5. Observe the Fuel Level Sensor voltage parameter with a scan tool.

Is the fuel level voltage at the specified value?

5 V

Go to Step 3

Go to Step 5

3 |

1. Jumper the fuel level sensor signal circuit and low reference circuits together.
2. Observe the Fuel Level Sensor voltage parameter with a scan tool.

Is the fuel level sensor voltage near the specified value?

5 V

Go to Step 4

Go to Step 6

4 |

1. Remove the fuel sender assembly. Refer to one of the following:

• | Fuel Sender Assembly Replacement for the 1.8 L (L79) engine

• | Fuel Sender Assembly Replacement for the 1.8 L (LDA) engine

• | Fuel Sender Assembly Replacement for the 2.0 L (Diesel) engine

• | Fuel Sender Assembly Replacement for the 2.0 L (L34 GMDAT) engine

2. Inspect for the following:

• | A stuck fuel level sensor (i.e. the fuel strainer interfering with the sender float arm.)

• | Foreign material in the fuel tank (ice)

• | A fuel tank that is deformed

3. If you find a condition, repair the condition, as necessary.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 7

5 | Test the fuel level signal sensor circuit for an open or high resistance. Refer to Testing for Continuity and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 8
6 | Test the low reference circuit and the fuel level signal circuit for an open or high resistance. Refer to Testing for Continuity and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 8
7 | Replace the fuel level sender assembly. Refer to one of the following:

• | Fuel Sender Assembly Replacement for the 1.8 L (L79) engine

• | Fuel Sender Assembly Replacement for the 1.8 L (LDA) engine

• | Fuel Sender Assembly Replacement for the 2.0 L (Diesel) engine

• | Fuel Sender Assembly Replacement for the 2.0 L (L34 GMDAT) engine

Did you complete the replacement?

--

Go to Step 10

--

8 | Test for an intermittent and for a poor connection at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9
9 | Replace the ECM. Refer to Control Module References. Did you complete the replacement? | -- | Go to Step 10 | --
10 |

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 11

Go to Step 2

11 | 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