For 1990-2009 cars

## DTC P0462 3.6L (LY7)

### 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.

### DTC Descriptor

DTC P0462: Fuel Level Sensor 1 Circuit Low Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Fuel Level Sensor Reference Voltage Circuit | P0462 | -- | -- | P0461
Fuel Level Sensor Signal Circuit | P0462 | P0463 ¹ P0464 | P0463 | P0461
Fuel Level Sensor Low Reference Circuit | -- | P0463 ¹ P0464 | P0463 | P0461
¹Fuel Gage Inaccurate or Inoperative

### Circuit/System Description

The primary fuel level sensor and the secondary fuel level sensor change resistance in response to fuel level. The engine control module (ECM) monitors the signal circuit of the primary fuel level sensor and the secondary fuel level sensor in order to determine the fuel level. When the fuel tanks are full, the resistances of both fuel level sensors are low, and the ECM senses a low signal voltage on both the signal circuit of the primary fuel level sensor and the signal circuit of the secondary fuel level sensor. When the fuel tanks are empty, the resistances of the fuel level sensors are high, and the ECM senses a high signal voltage. The ECM uses the signal circuits of the primary fuel level sensor and the secondary fuel level sensor in order to calculate the percentage of remaining fuel in the tanks. The ECM sends the fuel level percentage via the GMLAN serial data circuit to the instrument cluster in order to control the fuel gage. The fuel information is also used for misfire, evaporative emission (EVAP), and other on-board diagnostics.

### Conditions for Running the DTC

• | The engine keeps running.

• | The ignition 1 voltage is between 10.5-18 volts.

• | DTC P0642 runs continuously once the above condition is present for 60 seconds.

### Conditions for Setting the DTC

The sensor output is less than 0.25 volt.

### Action Taken When the DTC Sets

• | The fuel gage defaults to empty.

• | The driver information center (DIC) displays the FUEL LEVEL LOW message.

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

• | The control module records the operating conditions at the time of the failure. The first time the diagnosis fails, the control module stores this information into the Failure Records. If the diagnosis 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 into the Freeze Frame and updates the Failure Records.

### Conditions for Clearing the DTC

• | The control module turns OFF the MIL after 4 consecutive ignition cycles that the diagnosis runs and does not fail.

• | A current DTC, Last Test Failed, is cleared when the diagnosis runs and passes.

• | A history DTC is cleared after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnosis.

• | Use a scan tool in order to clear the MIL and the DTC.

### Reference Information

#### Fuel Level Specifications

Fuel Level Specifications

#### Schematic Reference

• | Instrument Cluster Schematics

• | Engine Controls Schematics

#### Connector End View Reference

• | Component Connector End Views

• | Engine Control Module Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Diagnostic Trouble Code (DTC) List - Vehicle

### Circuit/System Verification

With the scan tool installed and the ignition ON, verify that the Fuel Tank Level Remaining parameter in the ECM EVAP Data List indicates a value at or greater than 4.9 volts.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the fuel level sensor.
2. Ignition ON, use a scan tool to verify that the Fuel Tank Level Remaining parameter is less than 0.2 volt.

⇒ | If the parameter is greater than 0.2 volt, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.

3. If all circuits test normal, test or replace the fuel level sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Primary Fuel Level Sensor Replacement

• | Control Module References for ECM replacement, setup, and programming

## DTC P0462 3.6L (LH2)

### 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.

### DTC Descriptor

DTC P0462: Fuel Level Sensor 1 Circuit Low Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Fuel Level Sensor Reference Voltage Circuit | P0462 | -- | -- | P0461
Fuel Level Sensor Signal Circuit | P0462 | P0463 ¹ P0464 | P0463 | P0461
Fuel Level Sensor Low Reference Circuit | -- | P0463 ¹ P0464 | P0463 | P0461
¹Fuel Gage Inaccurate or Inoperative

### Circuit/System Description

The primary fuel level sensor and the secondary fuel level sensor change resistance in response to fuel level. The engine control module (ECM) monitors the signal circuit of the primary fuel level sensor and the secondary fuel level sensor in order to determine the fuel level. When the fuel tanks are full, the resistances of both fuel level sensors are low, and the ECM senses a low signal voltage on both the signal circuit of the primary fuel level sensor and the signal circuit of the secondary fuel level sensor. When the fuel tanks are empty, the resistances of the fuel level sensors are high, and the ECM senses a high signal voltage. The ECM uses the signal circuits of the primary fuel level sensor and the secondary fuel level sensor in order to calculate the percentage of remaining fuel in the tanks. The ECM sends the fuel level percentage via the GMLAN serial data circuit to the instrument cluster in order to control the fuel gage. The fuel information is also used for misfire, evaporative emission (EVAP), and other on-board diagnostics.

### Conditions for Running the DTC

DTC P0462 runs continuously.

### Conditions for Setting the DTC

• | The primary fuel level signal is less than 0.5 volt.

• | It occurs 240 times in 300 times of test.

### Action Taken When the DTC Sets

• | The fuel gage defaults to empty.

• | The driver information center (DIC) displays the FUEL LEVEL LOW message.

• | DTC P0462 is a type B DTC.

### Conditions for Clearing the DTC

DTC P0462 is a type B DTC.

### Reference Information

#### Fuel Level Specifications

Fuel Level Specifications

#### Schematic Reference

• | Instrument Cluster Schematics

• | Engine Controls Schematics

#### Connector End View Reference

• | Component Connector End Views

• | Engine Control Module Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Scan Tool Data List

### Circuit/System Verification

With the scan tool installed and the ignition ON, verify that the Fuel Tank Level Remaining parameter in the ECM EVAP Data List indicates a value at or greater than 4.9 volts.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the fuel level sensor.
2. Ignition ON, scan tool installed, use a scan tool to verify that the Fuel Tank Level Remaining parameter is less than 0.2 volt.

⇒ | If the parameter is greater than 0.2 volt, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.

3. If all circuits test normal, test or replace the fuel level sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Primary Fuel Level Sensor Replacement

• | Control Module References for ECM replacement, setup and programming