P0231 — Fuel Pump Secondary Circuit Low
High severityWhat it means
P0231 is stored when the engine control unit sees a fault involving the fuel pump control circuit. The fuel pump delivers fuel from the tank to the engine at the required pressure; a control-circuit fault can starve the engine of fuel. A “low” reading means the signal is stuck near the bottom of its range, which usually points to a short to ground or an internally failed sensor.
Common symptoms
- The live reading sits abnormally low or at zero
- Hard starting or a no-start
- Stalling or power loss under load
- Sputtering at higher speed
Likely causes
- Signal wire shorted to ground
- Internally failed sensor pulling the signal low
- A worn fuel pump or pump relay/driver module
- A wiring, connector or ground fault
What to check first
- Compare the live signal against a known-good range and check for a short to ground
- Check fuel pressure and listen for the pump priming at key-on
- Inspect the pump relay, fuse and wiring
Can you keep driving?
A failing fuel pump can leave you stranded without warning — treat it as urgent.
Frequently asked questions
What is the most common cause of P0231?
The most likely cause is: Signal wire shorted to ground. Several other faults can set P0231 as well, so confirm the real cause with live data and the checks above before replacing any parts.
Can I just clear P0231 and keep driving?
Clearing P0231 with an OBD2 scanner turns the warning light off, but if the underlying fault has not been repaired the code will usually come back within a few drive cycles. Fix the cause first, then clear the code to confirm the repair worked.
How serious is P0231?
P0231 is a high-severity code. Diagnose and repair it as soon as possible, because continuing to drive can cause further damage or leave you stranded.
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