P0231
Fuel Pump Secondary Circuit Low
The voltage on the secondary side of the fuel pump circuit is below the expected level when the pump is commanded on. Often caused by a failed pump motor, corroded ground, or wiring fault.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Check engine light on
- Hard start, no start, or stalling under load
- Power loss especially at high load or rpm
- Possible long cranking time
Common causes
Ordered by how often each turns out to be the cause.
- Fuel pump motor failed or wornCommon
- Pump ground point corrodedPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Fuel Pump
- Fuel Pump Wiring
P0231 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.