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.

### DTC Descriptor

DTC P0461: Fuel Level Sensor Performance
DTC P0462: Fuel Level Sensor Circuit Low Voltage
DTC P0463: Fuel Level Sensor Circuit High Voltage
DTC P2066: Fuel Level Sensor 2 Performance
DTC P2067: Fuel Level Sensor 2 Circuit Low Voltage
DTC P2068: Fuel Level Sensor 2 Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Fuel Level Sensor 1 Signal | P0462 | P0463 | P0463 | P0461
Fuel Level Sensor 2 Signal | P2067 | P2068 | P2068 | P2066
Low Reference | -- | 1 | P0463, P2068 | P0461, P2066
1. Fuel gage inoperative

### Circuit/System Description

The primary fuel level sensor and the secondary fuel level sensor change resistance based on fuel level. The engine control module (ECM) monitors the signal circuits of the primary fuel level sensor and the secondary fuel level sensor in order to determine the fuel level. When the fuel tank is full, the resistances of both fuel level sensors are low and the ECM senses a low signal voltage on both the signal circuits of the primary fuel level sensor and the secondary fuel level sensor. When the fuel tank is 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 tank. The ECM sends the fuel level percentage via High Speed CAN-Bus to the body control module (BCM). The BCM then sends the fuel level percentage via Low Speed CAN-Bus to the instrument cluster in order to control the fuel gage.

### Conditions for Running the DTC

• | The engine is running

• | The system voltage is between 11 V and 16 V

### Conditions for Setting the DTC

#### P0461 or P2066

• | The ECM detects a difference between the fuel consumed by the engine and change of the fuel level signal of less than 1 L (0.26 gal) over a range of 30 L (7.92 gal) or 45.6% of the primary fuel tank.

• | The above condition is present for about 300 seconds.

#### P0462 or P2067

• | The signal voltage is less than 0.25 V.

• | The above conditions must be met for 5 s.

#### P0463 or P2068

• | The signal voltage is greater than 4.7 V.

• | The above conditions must be met for 5 s.

### Action Taken When the DTC Sets

• | P0461, P0462, P0463, P2066, P2067 and P2068 are Type B DTCs

• | The fuel gage defaults to empty

• | The low fuel indicator illuminates

### Conditions for Clearing the DTC

• | P0461, P0462, P0463, P2066, P2067 and P2068 are Type B DTCs

• | The DTC becomes history when the conditions for setting the DTC are no longer present.

• | The history DTC clears after 40 malfunction-free warm-up cycles.

### Diagnostic Aids

The following engines have only one fuel level sensor

• | LDE

• | 2H0

• | LLU

• | LCD

• | LBX

• | LBS

### Reference Information

#### Schematic Reference

Instrument Cluster Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Instrument Cluster Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

Ignition ON, observe the scan tool ECM - Fuel Level Sensor parameter. The reading should be between 1 V and 4 V.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate sensor listed below.

• | B46A Fuel Level Sensor - Primary with LDK, LBW

• | B46B Fuel Level Sensor - Secondary with LDK, LBW, LBY

• | G12 Fuel Pump with LDE, 2H0, LLU, LCD, LBX, LBS

2. Ignition OFF, test for less than 5 Ω between the low reference circuit terminal 2 and ground.

⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

3. Ignition ON, verify the scan tool ECM - Fuel Level Sensor parameter is greater than 4 V.

⇒ | If less than the specified range, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

4. Install a 3A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the scan tool ECM - Fuel Level Sensor is less than 1 V.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

5. If all circuits test normal, test or replace the appropriate sensor.

### Component Testing

#### Static Test

1. Ignition OFF, disconnect the harness connector at the appropriate sensor.

• | B46A Fuel Level Sensor - Primary with LDK, LBW

• | B46B Fuel Level Sensor - Secondary with LDK, LBW, LBY

• | G12 Fuel Pump with LDE, 2H0, LLU, LCD, LBX, LBS

2. Test for 20-300 Ω between the signal terminal 1 and the low reference circuit terminal 2.

⇒ | If not within the specified range, replace the appropriate sensor.

3. Test for infinite resistance between each terminal and the sensor housing/case.

⇒ | If less than the specified value, replace the appropriate sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Fuel Sender Assembly Replacement for LDE, H20

• | Fuel Level Sensor Replacement for LDK

• | Fuel Sender Assembly Replacement for LBY, LCD, LBX, LBS

• | Fuel Pump Flow Control Module Replacement for LBW

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