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P0232 Generic (SAE)

Fuel Pump Secondary Circuit High

Updated 2026-10-02 · Fuel & air metering (injector circuit)

Severity
Medium
Typical repair cost
20 – 500 EUR
System
Powertrain

What it means

The ECM detected battery voltage on the fuel pump feed when the pump should have been switched off - for instance several seconds after key-off, or with the engine stalled and no crank signal present. This indicates the secondary circuit is being powered from an unintended source: welded relay contacts, a relay driver stuck on in the ECM or fuel pump control module, or a feed wire shorted to another 12 V circuit. Unlike the low code, the engine usually runs normally, but the pump may run with the key off and the safety cut-off after a crash or stall is defeated.

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Symptoms

  • Fuel pump audible with the key off or after the engine has been shut down
  • Battery drained overnight
  • Check Engine light with P0232, engine otherwise running normally
  • Hard start after a hot soak because fuel pressure stayed high and vaporized fuel in the rail
  • Occasionally no symptom at all - found only on a scan

Common causes

  1. Fuel pump relay contacts welded or stuck closed after years of high-current cycling
  2. ECM or fuel pump control module driver transistor shorted (stuck on)
  3. Pump feed wire shorted to a constant 12 V circuit (battery feed, tail light, trailer wiring)
  4. Aftermarket alarm, remote start or fuel pump bypass wired into the pump feed
  5. Wrong relay fitted - a jumper or a normally-closed relay in the fuel pump position
  6. Water in the fuse box bridging the pump feed to an adjacent live terminal

How to diagnose

  1. Key off, wait 10 seconds, then measure voltage at the pump fuse or the pump connector: it must be 0 V. Any battery voltage confirms the pump feed is live when it should not be.
  2. Pull the fuel pump relay with the key off: if the voltage at the pump feed disappears, the relay is the problem (welded contacts) or the ECM is holding the coil on. Measure the coil control pin - it should be at 12 V (not pulled to ground) with the key off.
  3. If the ECM control pin is grounded with the key off, disconnect the ECM and re-check: ground gone means a stuck driver inside the ECM; ground still present means the control wire is shorted to ground in the harness.
  4. If the feed stays live with the relay removed, the pump wire is shorted to another live circuit; pull fuses one at a time until the pump feed drops to 0 V to identify the source circuit.
  5. Inspect for aftermarket wiring at the relay socket, under the dash and at the tank; a remote-start or alarm module tapping the pump feed is a frequent cause on used vehicles.
  6. After repair, verify the pump stops within 2-3 seconds of key-on without cranking and that the fuel pressure holds correctly, then clear the code and check for the fuel pump shutoff logic to work after a stall.

Frequently asked questions

The engine runs fine - do I really need to fix P0232?

Yes. A pump that cannot be switched off keeps pumping after a crash or a stall, which is a fire risk, and it will flatten the battery. It also means the relay or driver has failed and may fail the other way next.

Can I just unplug the relay when I park?

As a temporary measure to save the battery, yes, but it is not a repair. Find the welded relay or shorted wire.

Why did my battery die but the code only showed up later?

The ECM only runs the secondary-circuit high test under specific conditions (key-off delay, no crank signal). It may need a few cycles before it flags the fault even though the pump has been running overnight.

Related codes

P0230P0231P0627P0629P0685

Nearby codes in this group