P0231 code meaning
Fuel Pump Secondary Circuit Low
Powertrain system Generic code P02xx codes Check engine light
What P0231 means
The fuel pump circuit has two sides: the primary circuit is the engine module's output to the fuel pump relay coil (or to a pump control module), the secondary circuit is the power circuit from relay contact or module to the pump itself. P0231 means the secondary side reads low, and the meaning differs by system. Ford's relay systems read the voltage in the pump power circuit through a monitor wire: if it is missing with the pump commanded on – relay contact not closing, fuse missing, wire open or shorted to ground – the code sets after 2–5 s. GM pumps with their own power module report a short to ground as overcurrent at 18 A or more, setting the warning light in the first trip and switching the output off. The pump gets no voltage, so the engine will not start or stalls.
P0231 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0231
- Engine cranks but does not start
- Engine stalls while driving
- Check engine light on
- Blown fuel pump fuse
Common causes of P0231
- Most likelyPower wire from relay or module to pump shorted to ground (chafing at tank or underbody)
- Most likelyRelay contact not closing, fuse or battery feed to the relay missing
- PossiblePump motor jammed or shorted (high current)
- PossibleConnector at the tank flange corroded or burnt
- Less likelyPump control module faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel pumpFuel pump relayFuel pump control moduleFuel pump wiring
What each part of P0231 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 2 | Area: fuel and air metering (injector circuit). |
| 31 | The exact fault in that area. |
What to do next
- Note P0231 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0231
What does P0231 mean?
P0231 means "Fuel Pump Secondary Circuit Low". The fuel pump circuit has two sides: the primary circuit is the engine module's output to the fuel pump relay coil (or to a pump control module), the secondary circuit is the power circuit from relay contact or module to the pump itself. It is a generic code, so it means the same on every make.
Is it safe to drive with P0231?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0231 fail an emissions test?
Yes, it can. P0231 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0231 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0231 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.