Fuel and air

P0233 — Fuel Pump Secondary Circuit Intermittent

Severity: medium Drive with care, to a shop

What P0233 means

P0233 means the engine control module intermittently detects incorrect voltage or lost continuity in the secondary control circuit of the fuel pump. The module normally switches the pump on through a relay or a dedicated pump control module and monitors the circuit. When the signal drops out and then returns, it stores this intermittent fault code.

Symptoms

  • Check Engine Light on
  • Engine stalls or hesitates under load
  • Hard starting or long cranking
  • Sudden engine shut-off while driving
  • Intermittent loss of power
  • Occasional no-start that later goes away

Possible causes

  1. Failing fuel pump relay
  2. Damaged wiring or poor connections in the pump circuit
  3. Corroded or loose connectors and ground points
  4. Faulty fuel pump control module (if equipped)
  5. Intermittent short or open in the PCM pump driver circuit
  6. Worn or internally failing fuel pump

How to diagnose

  1. Scan all codes and review freeze frame data to see when the fault occurred
  2. Check the fuel pump fuse and its socket
  3. Swap in a known-good relay, or exchange it with an identical one, and retest
  4. Inspect the connectors at the relay, control module and pump for corrosion, heat damage and loose terminals
  5. Wiggle the harness with the key on and listen for the pump humming to cut out
  6. Measure supply voltage and voltage drop on the pump power and ground while it runs
  7. Check the control signal from the PCM or pump module with a multimeter or scope
  8. Measure pump current draw and fuel pressure at the rail

Common fixes

  • Replace the faulty fuel pump relay
  • Repair damaged wiring and clean or replace corroded connectors and terminals
  • Replace the fuel pump control module
  • Replace the fuel pump if internal failure is confirmed
  • Repair or replace the PCM if the driver circuit is confirmed faulty

Questions and answers

What does code P0233 mean?

The PCM has detected an intermittent fault in the fuel pump secondary control circuit. The relay, connectors or wiring are the usual culprits, and the pump itself less often.

Can I drive with P0233?

Only for short distances and with care. The engine may stall suddenly, so fix it as soon as you can.

Why does the code come and go?

It is usually a poor connection or a worn relay that fails only with vibration, heat or certain loads.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.