Possible causes

– Blown Fuel Pump fuse
– Open Fuel Pump Monitor Circuit
– Faulty Fuel Pump Relay
– Damaged Engine Control Module (ECM)

Tech notes

For some FORD models:
1. Disconnect the inertia switch harness connector
2. Turn key to ON position (Engine OFF)
3. Measure voltage of circuit between inertia switch harness connector and ground
4. If battery voltage is found, replaced Inertia Switch
5. Clear codes.

When is the code detected?

The code will be set if a low voltage on the control circuit of the fuel pump relay is detected by the ECM.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P0231 FORD Description

The Engine Control Module (ECM) provides ignition positive voltage to the coil side of the fuel pump relay. When the ignition switch is first turned ON, the ECM energizes the fuel pump relay, which applies power to the fuel pump. The ECM enables the fuel pump relay as long as the engine is cranking or running, and crankshaft reference pulses are received. If no crankshaft reference pulses are received, the ECM de-energizes the fuel pump relay after 2 seconds. The ECM monitors the voltage on the fuel pump relay control circuit.

FORD Technical Service Bulletins for P0231 code