P0231 Code: Fuel Pump Secondary Circuit Low
🟠 Moderate severity · drivable
Drivable if the engine runs, but a weak fuel supply can cause stalling or a no-start, so fix it soon.
What P0231 means
The voltage on the fuel pump's secondary circuit — the power feed from the relay to the pump — reads lower than expected. The pump may not be getting full power, so it can't deliver enough fuel under load.
Symptoms
- Check engine light is on
- Hard starting
- Loss of power under load
- Engine stalling or hesitation
Common causes
- most common: Corroded or high-resistance wiring and connector
- common: Faulty fuel pump relay with weak contacts
- common: Failing fuel pump drawing too much current
- less common: Poor ground connection in the pump circuit
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Inspect and repair the fuel pump wiring and connector | Mechanic | $50–150 |
| Replace the fuel pump relay | Yes | $20–60 |
| Replace a failing fuel pump | Mechanic | $300–800 |
Frequently asked questions
Can I drive with a P0231 code?
Only if the engine is running normally, and with caution — low fuel pressure can cause stalling or a no-start. Fix it soon.
What is the most common cause of P0231?
Corroded or high-resistance wiring and connectors that drop voltage to the fuel pump.
How much does it cost to fix a P0231?
Typically $20–60 for a relay, $50–150 for wiring repairs, or $300–800 if the fuel pump is replaced.
Related codes
P0230
P0230 Code: Fuel Pump Primary Circuit Malfunction
P0232P0232 Code: Fuel Pump Secondary Circuit High
P0233P0233 Code: Fuel Pump Secondary Circuit Intermittent
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.