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P0230 — Fuel Pump Primary Circuit

By Mr Auto Fixer — Professional Mechanic, 20+ Years Experience

The primary fuel pump circuit (relay, fuse, or wiring) has a fault. The fuel pump cannot run or runs erratically.

High — Act Now
Last checked: May 2026

What Is P0230?

P0230 means the ECU has detected a fault in the fuel pump primary control circuit — the electrical circuit that commands the fuel pump relay to operate the fuel pump. The ECU monitors this circuit for correct operation, and when it detects an open circuit, short circuit, or missing feedback signal, P0230 is stored.

Without a functioning fuel pump circuit, the engine will not run or will stall immediately after startup. P0230 is a circuit fault — it does not necessarily mean the pump itself has failed. The most common causes are a blown fuel pump fuse, failed fuel pump relay, or a break in the wiring between the relay and pump. Always check the electrical supply before replacing the fuel pump itself.

Common Symptoms

  • Engine will not start
  • Engine starts but immediately stalls
  • Engine management light on
  • No fuel pump prime sound when ignition is turned on
  • Loss of power leading to stalling while driving

Common Causes

Blown Fuel Pump FuseThe fuel pump fuse has blown due to a pump drawing excess current or a wiring short. Always the first thing to check.
Failed Fuel Pump RelayThe relay that switches battery voltage to the fuel pump has failed open-circuit. The ECU triggers the relay but the pump receives no power.
Broken Wiring to Fuel PumpA break in the wiring between the relay and the in-tank fuel pump. Common failure points are where the loom enters the fuel tank area or near heat sources.
Corroded Fuel Tank ConnectorThe multi-pin connector on top of the fuel pump assembly inside the tank becomes corroded, breaking the electrical path to the pump motor.
Failed Fuel Pump MotorThe pump motor has seized or failed, drawing excessive current that blows the fuse or triggers ECU over-current protection.

How to Diagnose P0230

1

Check Fuel Pump Fuse

Locate the fuel pump fuse in the main fuse box (usually inside the engine bay fuse box — check the lid diagram). Test with a multimeter or test light. Replace if blown. If the new fuse blows immediately, there is a short circuit in the pump wiring that must be located.

2

Test Fuel Pump Relay

Locate the fuel pump relay. With the ignition on, check for 12V at the relay output terminal using a multimeter. Swap the relay with an identical spare relay from another circuit and retest. A faulty relay is a very common cause of P0230.

3

Listen for Pump Prime Sound

Turn the ignition to position II without cranking. A healthy fuel pump primes for 2–3 seconds — you will hear a faint hum from near the fuel tank. Silence confirms no power is reaching the pump.

4

Check Wiring from Relay to Tank

Trace the fuel pump supply wire from the relay output to the top of the fuel tank. Check for breaks, heat damage, or corrosion at the fuel sender connector on the tank top.

5

Test Pump Motor Directly

Apply 12V directly to the pump motor connector at the tank to confirm whether the motor itself is alive. If it runs on direct power but not through the relay circuit, the fault is in the wiring or relay, not the pump.

Do Not Crank RepeatedlyExcessive cranking without fuel delivery can overheat the starter motor and damage the catalytic converter by flooding it with unburnt fuel vapour. Diagnose the electrical fault before repeated cranking attempts.

Verdict

Check fuse and relay first — these are the most common causes and cost nothing to diagnose and pennies to fix. Only move on to wiring and pump testing if fuse and relay are confirmed good. Replacing a fuel pump without checking these first is a common expensive mistake.

Mr Auto Fixer
Written by
Mr Auto Fixer
Qualified Mechanic20+ Years ExperienceUK Based

Professional UK mechanic with over 20 years of hands-on experience. All guides are based on real workshop repairs — not theory.

About Mr Auto Fixer
Common Questions

Frequently Asked Questions

Apply 12V directly to the pump motor terminal at the fuel tank connector. If the pump runs, the motor is alive — the fault is in the relay or wiring. If the pump does not run on direct power, the pump motor has failed.
Yes. Fuel pump motors can fail suddenly, particularly on high-mileage vehicles. However, a sudden no-start is more often a relay or fuse fault than a pump failure. Always check the electrical supply before assuming the pump has failed.
Not always. An intermittent circuit fault can cause the engine to stall unpredictably or cut out under load when the circuit briefly opens. Intermittent P0230 is more likely a relay or connector fault than a pump failure.
Usually in the engine bay fuse and relay box. On some vehicles it is in the interior fuse box under the dashboard or in the boot area near the battery. Always refer to the fuse box diagram on the lid.
It depends on which warning light the code is triggering. Since 2018, any car presenting with an illuminated amber Engine Management Light (EML) at the MOT is a Major failure under DVSA rules — even if the car drives perfectly. A red warning light is always a Major or Dangerous failure depending on context. If clearing the fault makes the light go out and the code does not reappear during the pre-test drive, you will pass; if the code returns within minutes of clearing, the underlying fault must be fixed before MOT day. A tester is required to fail the car on the light being on, regardless of whether the underlying fault is something safety-critical or not. For codes that affect emissions specifically (catalyst, lambda, EGR), the car may also fail the actual emissions check. Fix the cause, clear the code, and drive the car for a few miles before the test.
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