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DTC codes / P02xx · Fuel and air metering (injector circuits) / P027B

P027BFuel Pump Module B Control Circuit Range/Performance

P027B indicates that the powertrain control module (PCM) has detected an out-of-range or performance issue with the control circuit for fuel pump module B. The PCM monitors the circuit for expected voltage or current behavior and sets this code when the signal does not match the commanded state within a calibrated time or range.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering (injector circuits)

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms.
  • Engine may crank but fail to start or start with difficulty due to insufficient fuel delivery.
  • Intermittent stalling or hesitation during acceleration if the pump control is erratic.
  • Reduced engine power or limp mode in some vehicles as a protective strategy.
  • Audible fuel pump operation may be absent when the key is turned to the run position.

Common causes, most likely first

  1. Faulty fuel pump module B (internal pump motor or control electronics failure).
  2. Damaged or corroded wiring or connectors in the fuel pump control circuit.
  3. Blown fuse or faulty relay supplying power to the fuel pump module.
  4. PCM software or hardware issue misinterpreting the control circuit signal.
  5. Poor ground connection for the fuel pump module or PCM.
  6. Aftermarket accessories or improper previous repairs interfering with the circuit.

How to diagnose and fix it

  1. Verify battery voltage and inspect the fuel pump fuse and relay; replace if blown or faulty.
  2. Perform a visual inspection of the fuel pump module wiring and connectors for damage, corrosion, or loose pins.
  3. Use a scan tool to command the fuel pump on and off while listening for pump operation and checking for voltage at the pump connector.
  4. Measure resistance and voltage drop on the control circuit between the PCM and fuel pump module to identify high resistance or open circuits.
  5. Check the fuel pump module ground circuit for integrity and clean or tighten as needed.
  6. If the circuit tests good, substitute a known-good fuel pump module or perform a bench test to confirm the fault.
  7. Reprogram or replace the PCM only after all other causes have been ruled out and technical service bulletins have been reviewed.

Don't overlook the fuel pump control module

  • Many vehicles use a separate fuel pump control module (FPCM) that can fail independently of the in-tank pump, and this code often points to that module rather than the pump itself.
  • A weak battery or charging system issue can cause erratic fuel pump control signals and set P027B without any fault in the pump circuit.
  • Intermittent faults may only appear under specific conditions such as low fuel level, high temperature, or vibration, so a wiggle test of the harness while monitoring live data is essential.
  • Some aftermarket alarm or remote start installations tap into the fuel pump circuit and introduce resistance or interference that triggers this code.
  • P027B can be set by a PCM calibration issue, so checking for software updates before replacing hardware can save unnecessary repairs.

Can I keep driving with P027B?

If the engine starts and runs normally, you can drive cautiously to a repair shop, but avoid hard acceleration and long trips. If the engine stalls, hesitates, or fails to start, stop driving and have the vehicle towed to prevent safety risks.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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