P0231 fault code: Fuel Pump Secondary Circuit Low

Last updated · OBDCode UK editorial

Can I drive with P0231? — Limit driving

Limit driving. A low secondary pump signal can mean the pump is not confirmed running. Stop if the engine dies, you smell fuel, or power collapses.

P0231 means “Fuel Pump Secondary Circuit Low” — a fuel and injector circuits fault in the powertrain. Limit driving. The fuel-pump secondary (monitor) circuit is reading too low, so the computer cannot confirm the pump is actually being driven.

Can I DIY?

Do not DIY this repair. We do not publish DIY repair or strip-down steps for this code on this page. Read codes and observe only; leave the repair to a qualified garage.

Do not DIY this repairDIY boundary
ToolsSpecialist tools or workshop equipment — typically a professional garage job.

This fault is in the professional-only category. We do not publish strip-down or fitting steps on this page. Use a qualified garage.

Hot systems

Never open a hot coolant cap — pressure can scald you. Exhaust and catalytic converter get hot enough to burn and ignite debris. Stay clear of electric fans; they can run after shut-off.

P02xxFuel and injector circuits
MOT fail riskif the warning light stays on

What does P0231 mean?

P0231 is a generic (SAE standard) powertrain code reported by your car’s engine control unit. It sits in the P02xx block, which covers fuel and injector circuits. The stored description is “Fuel Pump Secondary Circuit Low”. The code itself tells you which circuit or system tripped the fault — not always the exact part that failed.

Will P0231 fail an MOT?

An illuminated engine management light is a Major defect at MOT (automatic fail) until the fault is repaired and the light stays off. The lamp rule still applies even if the engine currently runs.

Before booking your test, check what usually fails on your car: see our MOT pass rates by make and model, built from 33.1 million DVSA tests.

What the MOT data says

No MOT certificate item corresponds to this code; MOT outcome data cannot be shown.

Related guides

Car diagnostic test cost: compare the scopeUK booking marketplaces currently publish diagnostic averages of about £52–£65. Engine management light on: steady or flashing?A steady engine management light means the computer has stored a fault. Drive with caution and get the code read. A flashing light is different — stop when it is safe.
P0200Injector Circuit/Open P0201Injector Circuit/Open - Cylinder 1 P0202Injector Circuit/Open - Cylinder 2 P0203Injector Circuit/Open - Cylinder 3 P0204Injector Circuit/Open - Cylinder 4 P0205Injector Circuit/Open - Cylinder 5 P0206Injector Circuit/Open - Cylinder 6 P0207Injector Circuit/Open - Cylinder 7

P0231 — quick answers

Is it safe to drive with P0231?

Limit driving. Limit driving. A low secondary pump signal can mean the pump is not confirmed running. Stop if the engine dies, you smell fuel, or power collapses.

Can I fix P0231 myself?

Do not DIY this repair. We do not publish DIY repair or strip-down steps for this code on this page. Read codes and observe only; leave the repair to a qualified garage. Specialist tools or workshop equipment — typically a professional garage job.

Will P0231 fail my MOT?

An illuminated engine management light is a Major defect at MOT (automatic fail) until the fault is repaired and the light stays off. The lamp rule still applies even if the engine currently runs.

Fault-code identifiers are standard diagnostic facts. Their explanations and diagnostic guidance on this site are original editorial summaries, not reproduced SAE wording. MOT defect rules reflect the DVSA MOT inspection manual (2026). This page is general guidance for UK drivers, not a substitute for a professional diagnosis.