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

P027B Fuel Pump Module B Control Circuit Range/Performance

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. P027B means pump module B receives an invalid command or its feedback does not match. Ford's module signals this with a 20 % (±4 %) duty cycle on its monitor line, checked continuously at 11–16 V over 2–5 s; on Ford commercial vehicles the module B monitor line runs via the smart relay module and CAN to the engine module. Whether the warning light comes on depends on the vehicle.

Likely causes

Contact resistance or corrosion in the control or monitor line to module B
Pump control module B faulty
Ground problems
Relay module or CAN forwarding disturbed (Ford commercial vehicles)

Symptoms

  • Check engine light (vehicle-dependent)
  • Fuel shortage when running from the second tank
  • Surging, lack of power

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

P025BP025AP027CP027DP2632P26EA

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