P0230 to P0232: fuel pump primary circuit faults

The fuel pump lives in the tank and draws real current. It is not switched directly by the ECU — a relay does the heavy work, and the ECU controls the relay.

P0230 to P0232 describe faults in that control path.

Code	Meaning
P0230	Fuel pump primary circuit malfunction
P0231	Fuel pump secondary circuit low
P0232	Fuel pump secondary circuit high

Primary is the low-current control side; secondary is the high-current feed to the pump. That single fact tells you where to look.

The symptom you will actually have

An engine that cranks normally and does not start, or one that starts and stalls immediately.

Cranking normally is the useful detail: it rules out the battery, the starter and most of the electrical system. The engine is turning and not getting fuel.

Engine cranks but won’t fire.

The two-second listening test

Before any tools: switch the ignition to on, without cranking, and listen at the fuel filler or the rear seat.

A healthy system runs the pump for one to three seconds to prime the rail, then stops. You can usually hear it as a soft whirr.

What you hear	Meaning
A short whirr, then silence	Pump and relay working
Nothing at all	No power reaching the pump
Continuous running that never stops	Relay stuck closed or control fault
A loud whine	Pump straining — often a blocked filter or strainer

That last one matters. A pump forced to work against a restriction gets hot and dies early. The noise is the warning.

Causes in order

1. The relay

Cheapest, most accessible, most common. Relay contacts pit and burn from switching an inductive load thousands of times.

The classic test: find an identical relay elsewhere in the box — horn, air conditioning, something non-critical — and swap them. If the fault follows the relay, you are done.

Fuses and relays basics for owners.

2. Fuses

Usually two: one for the relay coil, one for the pump feed. Check both, and check them with a meter rather than by eye — a fuse can look intact and be open.

3. Inertia or fuel cut-off switch

Many vehicles have a crash sensor that cuts the pump. A sharp pothole or a minor knock can trip it, and the car then behaves exactly like a dead fuel pump.

Find out whether your vehicle has one and where it is. Resetting it is free; replacing a pump because of it is not.

Pothole damage: what to check.

4. Wiring and connectors

The feed to the tank runs the length of the car underneath it. Corrosion at the tank connector is common on older vehicles in salted-road climates.

5. The pump

Last. Pumps do fail, but they fail after the four items above in frequency, and they are the most expensive to replace.

What the data can and cannot tell you

Generic OBD-II does not usually expose fuel pump duty directly, but two readings help:

Fuel rail pressure, where available, tells you whether the pump is delivering: P0087 fuel rail pressure too low.

System voltage at cranking. A voltage that collapses under crank makes several systems misbehave at once, and a marginal battery can look like a fuel delivery fault.

Related codes on newer vehicles

Many modern cars use a fuel pump control module rather than a simple relay, allowing variable pump speed. Those systems produce different codes:

• P0627 to P0629 — fuel pump control circuit: P0627 to P0629.
• U0109 — lost communication with the fuel pump control module, which is a network fault rather than a power fault.

If your vehicle has a control module, the relay-swap test does not apply, and the diagnosis moves to the module and its network connection.

Step by step

1. Listen for the prime with ignition on.
2. Check both fuses with a meter.
3. Check the inertia switch if the vehicle has one.
4. Swap the relay with an identical one.
5. Check for voltage at the pump connector during the prime.
6. Only then consider the pump.

You can check this yourself. Pair an ELM327 adapter, open the free tier of the app and check fuel rail pressure during cranking. Pressure that never builds while the pump can be heard running points somewhere quite different from silence at the tank.