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

P027D Fuel Pump Module B Control Circuit High

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. P027D means the control circuit to pump module B reads high, typically a short to voltage – the counterpart of P025D. Ford lists it in the low-pressure lift pump monitor of its 2023 diesels, monitored continuously and set within 0.5 s, without its own threshold. Pump B may then run all the time or not at all.

Likely causes

Control line to module B shorted to voltage
Moisture or corrosion in the connector
Pump control module B faulty

Symptoms

  • Check engine light on
  • Pump B runs all the time or not at all
  • Starting problems

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–700
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

P025DP027CP027AP027BP2634

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