Fuel Pump Primary Circuit Malfunction


The PCM has detected an open in the primary fuel pump control circuit.

Code Set Parameters

Abnormal voltage readings that vary by greater than 10-percent of the manufacturer’s referenced voltage will cause a code to be stored and a malfunction indicator lamp to be illuminated. These abnormal readings are detected by the PCM.


A stored code and illuminated service engine soon lamp are normally accompanied by a NO-START condition.

Common Causes

Likely causes are a faulty fuel pump relay, a faulty PCM, the fuel pump safety interrupt switch has been activated (Ford), or an open circuit in the fuel pump wiring or connectors.

Common Misdiagnosis

The fuel pump is often condemned in error when this code is exhibited.


  • The fuel pump primary circuit could best be described as the circuit that supplies voltage to the fuel pump
  • The secondary circuit is the feedback circuit that provides input data about the fuel pump to the PCM
  • Any successful diagnosis of this code must include checking all related fuses and relays to ensure that the proper amount of voltage is present (typically this is battery voltage)
  • A scanner or code reader, a digital volt ohmmeter, and access to a manufacturer’s wiring schematic will be necessary to successfully diagnose this code
  • Begin your diagnosis with a visual inspection of all wiring and connectors
  • Repair or replace damaged, disconnected, shorted, or corroded wiring, connectors, and components as necessary
  • Always retest the system after repairs are completed to ensure success. If all system wiring, connectors, and components (Including fuses) appear to be in normal working order, connect the scanner (or code reader) to the diagnostic connector and record all stored codes and freeze frame data
  • This information can be extremely helpful in diagnosing intermittent conditions that may have contributed to this code being stored
  • After the codes are cleared, operate the vehicle to see if the code returns
  • If the code fails to immediately return, you may have an intermittent condition
  • Intermittent conditions can prove to be quite a challenge to diagnose and in extreme cases may have to be allowed to worsen before a correct diagnosis can be made. Test voltage at the fuel pump connector to determine if there is sufficient power and ground when the ignition key is in the start position
  • If the required voltage is present at the fuel pump, then suspect a shorted or faulty pump and repair as necessary
  • If there is no voltage at the pump (or reduced voltage is present) then the problem is likely in the electrical wiring or connectors
  • Technicians have reported corroded electrical connector faces that fail when placed under the load of engine startup
  • Some manufacturers also use fuel pump safety interrupter switches
  • Check to make sure that this switch has not been activated before performing an extensive diagnosis for nothing
  • Also be aware that plug-in type fuses can appear adequate when performing Key-on-engine-off testing and fail when placed under the load of engine start-up
  • It is critical that you test fuel pump and fuel injection related fuses under start-up conditions