What does it mean?
Here the signal from the gaseous fuel tank A level sender is sitting at or above the highest voltage the module will accept. With the sender wired as a variable resistance to ground, an open circuit anywhere in the signal or ground path leaves the module input pulled up to reference voltage, which is exactly the signature of this code. A functioning sender always presents some resistance to ground and therefore never reaches the top of the range, so the module rejects the value and stores the fault. The gas gauge typically reads full or goes dead, and the module loses the ability to warn the driver before the tank runs out. Because an open connection is far more likely than a genuinely over-full tank, the diagnosis is a continuity exercise.
Symptoms
- Gas fuel gauge reading full at all times or not moving at all
- MIL (check engine lamp) on with a gaseous fuel fault stored
- No low fuel warning, so the tank can empty without notice
- Sudden unplanned changeover to gasoline when the gas actually runs out
- Range display missing or clearly wrong
- Otherwise normal engine operation
Likely causes
- Open circuit in the sender signal wire or its ground under the vehicle
- Corroded, spread or backed-out terminal in the level sender connector
- Sender resistive track worn through or the wiper lifted off the track
- Connector left unlatched after tank, multivalve or exhaust work
- Signal wire shorted to reference or battery voltage from an adjacent circuit
- Incorrect sender fitted with a resistance range far above specification
- Module input circuit failure, the least likely cause
How to fix it
- Read the live fuel level value; a reading at maximum with a nearly empty tank confirms the circuit fault
- With the sender unplugged and the ignition on, jumper the signal pin to ground at the harness connector. A reading that swings to empty proves the wiring and module are good
- If the reading stays at maximum with the pin grounded, trace the signal wire and the ground circuit for an open
- Inspect the connector for spread or backed-out terminals, corrosion and a broken lock, and check the seal condition
- Measure the sender resistance at its own terminals; an infinite reading confirms an open track or lifted wiper
- Repair the open wire, terminal or ground and reseal the connection, then clear the code and verify the gauge follows the actual level
- Replace the level sender or multivalve assembly once the harness has been proven good