P0231: Fuel Pump Secondary Circuit Low
Do not keep driving
Expect poor starting, stalling or a loss of power under load. Ask for voltage to be measured at the pump while it runs, not just for continuity to be checked.
What this code means
The secondary fuel pump circuit — the power feed carrying current to the pump itself — is reading low. This is the high-current side of the system, so voltage drop across corroded connections is a real cause rather than a theoretical one: a pump that runs slowly because it is only receiving part of its supply will produce low pressure while testing as electrically continuous.
Likely causes
Start here
- Wiring shorted to ground · moderate
- Voltage drop from corroded pump connections · moderate
- Failed fuel pump · moderate
Less common
- Failed fuel pump relay · easy
- Corroded earth connection · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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