Fuel and air

P027D — Fuel Pump Module B Control Circuit High

Severity: medium Drive with care, to a shop

What P027D means

The engine control unit commands fuel pump module B (a pump driver or control module) and monitors the signal in that circuit. P027D sets when the voltage is higher than expected, for example from a short to power, a wiring fault or a failing module. As a result, fuel pressure may not match what the engine needs.

Symptoms

  • Check Engine light on
  • Hard starting or no-start
  • Misfire or rough idle
  • Hesitation and reduced power
  • Worse fuel economy
  • Occasional stalling

Possible causes

  1. Damaged wiring or connectors (short to power, open circuit, corrosion)
  2. Failed fuel pump module B or its control module
  3. Faulty fuel pump relay
  4. PCM/ECM fault or software issue
  5. Incorrect fuel pressure caused by another fuel system problem

How to diagnose

  1. Scan all codes and freeze frame data, record them, then clear the code and see if it returns
  2. Check the fuel pump fuse and relay
  3. Inspect connectors and harness near the tank, underbody and PCM for corrosion, chafing or moisture
  4. Check power and ground at the pump module connector using the factory wiring diagram
  5. Test the control signal wire for opens and shorts to power
  6. Measure fuel pressure with a gauge and compare it to spec
  7. Run the scan tool's active test on the pump module and driver
  8. If everything else checks out, test the PCM and look for software updates

Common fixes

  • Repair damaged wiring and clean or replace connectors
  • Replace the fuel pump relay
  • Replace fuel pump module B or its control module
  • Update software or replace the PCM if confirmed faulty

Questions and answers

What does P027D mean?

The PCM detected a high voltage in the control circuit of fuel pump module B. Wiring, connectors or the module itself are the usual culprits.

Can I drive with P027D?

A short trip to a shop is often possible, but the car may lose power or stall. If it starts poorly or hesitates badly, have it towed.

Do I need a new fuel pump right away?

No. Check the fuse, relay, connectors and wiring first, since an electrical fault is often the cause rather than the pump itself.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.