Loose, corroded or damaged connector at the fuel pump, relay or pump control module; Chafed, broken or high-resistance wiring in the pump feed or earth circuit; Failing fuel pump relay with worn contacts or dry joints; Worn fuel pump drawing excessive or erratic current; Blown or poorly seated fuse, or a corroded fuse box terminal; Faulty fuel pump driver or control module, where fitted; Inertia or impact safety switch intermittently opening, where fitted.

P0233

Fuel Pump Secondary Circuit Intermittent.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
2: AreaFuel and air metering (injector circuit)
33: FaultThe specific fault in that area

What it means

P0233 is the generic code for an intermittent fault in the secondary circuit of the fuel pump. The powertrain control module monitors the fuel pump's secondary circuit, which is often the feed to the pump or the relay-controlled supply. It has seen the voltage or current drop out, or fall outside its expected range, and then recover. The exact circuit layout depends on the make, model and engine.

Symptoms

Intermittent engine cutting out or stalling, especially over bumps
Long cranking or hard starting that comes and goes
Hesitation or loss of power under load
Engine misfire or surging at steady speed
Fuel pump not heard priming at key-on at times
Malfunction indicator lamp on, sometimes with the fault not returning straight away

Possible causes

Loose, corroded or damaged connector at the fuel pump, relay or pump control modulelikely
Chafed, broken or high-resistance wiring in the pump feed or earth circuitlikely
Failing fuel pump relay with worn contacts or dry jointslikely
Worn fuel pump drawing excessive or erratic currentpossible
Blown or poorly seated fuse, or a corroded fuse box terminalpossible
Faulty fuel pump driver or control module, where fittedrare
Inertia or impact safety switch intermittently opening, where fittedrare

How to diagnose

Read the stored and pending codes and the freeze frame data to see the conditions when the fault set, such as engine speed, load and battery voltage
Check for related codes, such as fuel pressure, fuel trim or battery voltage faults, and check any relevant technical service bulletins for the model
Inspect the fuel pump fuse, relay and their sockets for heat damage, corrosion or looseness
Inspect the wiring and connectors at the pump, usually accessed under the rear seat or boot floor, and at the control module for damage, water ingress and poor terminal tension
Wiggle-test the harness and connectors with the ignition on while watching live fuel pump command and fuel pressure data to try to reproduce the dropout
Measure the voltage at the pump during priming and while running, with the circuit loaded, and check the earth for voltage drop
Test the relay by swapping it with a known good identical one or by testing under load
Measure the pump's current draw and fuel pressure and compare with the manufacturer's specification for that engine

How to fix

Clean, repair or replace faulty connectors and terminals in the pump circuit
Repair or replace damaged wiring, including poor earth connections
Replace the fuel pump relay or fuse if it is faulty or has damaged contacts
Replace the fuel pump or pump assembly if current draw or pressure is out of specification
Replace the fuel pump control module if it is confirmed faulty, following the manufacturer's procedure
Clear the codes after the repair and road test to confirm the fault does not return

Can I keep driving?

Medium severity

The car may be driven for a short time, but the fault can cause stalling without warning, which is a safety risk in traffic. Get it diagnosed soon and avoid long journeys until it is fixed.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.