What does it mean?
P1234 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Electrical Fuel Pump Circuit Short to Battery .
Symptoms
- Fuel pump runs continuously, including with the ignition off
- Battery goes flat overnight and the pump becomes hot or noisy
- Fuel pressure higher than normal, rich running and a fuel smell near the tank
- Blown pump fuse and a resulting no-start
- Check engine lamp on with fuel pressure or pump circuit codes
Likely causes
- Pump feed wire chafed against the underbody or a tank strap and touching a live conductor
- Relay with welded or stuck contacts keeping the pump powered
- Corrosion or water in the pump connector bridging the feed to the control side
- Aftermarket wiring, an alarm cut-off or a fuel pump switch wired incorrectly
- Damaged control module output stage that can no longer isolate the circuit
- A repair splice made to the wrong wire in the rear harness
How to fix it
- Confirm the complaint: listen for a pump that keeps running after the ignition is switched off
- Pull the pump relay and see whether the pump stops, which separates a welded relay from a wiring short
- Fit a known good relay and retest
- Unplug the pump and check its feed wire for voltage with the ignition off
- Inspect the rear harness along the tank and underbody for chafe against metal and previous repairs
- Disconnect any added accessories or alarm connections spliced into the pump circuit
- Repair the wiring, measure current draw and confirm the pump switches off correctly before condemning the module