Powertrain, generic · Fuel and air metering (injector circuit)

P027A Fuel Pump Module B Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

On demand-controlled fuel systems the engine module does not drive the pump itself but sends a pump control module the desired pump output on a separate control line, usually as a duty cycle; the module reports back on a monitor line or via CAN. Module B is a second pump module, for example on dual-tank commercial vehicles. P027A is the counterpart of P025A: the control line from the engine module to pump module B is open or faulty. No manufacturer using P027A was found – Ford reports line faults of both modules together under P025A, GM only uses P025A; the description follows CARB's circuit monitoring requirement and Ford's module B check. If the second tank's pump gets no valid command, fuel may run short when running from that tank.

Likely causes

Control line to the pump module open or shorted, often along the frame
Connector at the pump module corroded or wet (module often mounted on the frame)
Pump control module faulty (input)
Module ground or supply poor

Symptoms

  • Check engine light (manufacturer-dependent)
  • Fuel shortage when running from the second tank
  • Starting problems, surging

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–600
Time1–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel pump control module bfuel pump control wiringengine control module

Related codes

P025AP027BP027CP027DP2632P26EA

References: law.cornell.edu, fordservicecontent.com, roushcleantech.com.