P0231 MERCEDES-BENZ – Fuel Pump Secondary Circuit Low

P0231 MERCEDES-BENZ Possible Symptoms

Engine Light ON (or Service Engine Soon Warning Light)

P0231 MERCEDES-BENZ Possible Causes

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

P0231 MERCEDES-BENZ 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.