Poor electrical connection or corrosion at the fuel pump module, driver module or their connectors; Damaged, chafed or high-resistance wiring in the pump control or feedback circuit; Worn or failing fuel pump unable to deliver the commanded output; Faulty fuel pump driver or control module; Low battery voltage or poor supply, earth or fuse and relay problems feeding the pump circuit; Restricted fuel filter or blocked pump inlet strainer causing the pump to work outside its expected range; Outdated or faulty ECU software where a manufacturer bulletin identifies it as a cause.

P027B

Fuel Pump Module B Control Circuit Range/Performance.

Generic
Powertrain
Generic code
High severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
2: AreaFuel and air metering (injector circuit)
7B: FaultThe specific fault in that area

What it means

P027B is a generic code meaning the engine control unit has found a range or performance problem in the control circuit of fuel pump module B. The ECU commands the pump module to deliver a certain output, then compares that command with the feedback signal or the resulting fuel pressure. If the two do not agree within an expected window for long enough, the code is set. It is mainly seen on vehicles with a driver module or a second pump arrangement, and the exact layout depends on the model and engine.

Symptoms

Engine cranks but starts slowly or not at all
Hesitation or loss of power under load
Engine stalling or cutting out intermittently
Rough running or misfire at higher demand
Engine warning light on, possibly with limp mode
Fuel pressure related fault codes stored alongside

Possible causes

Poor electrical connection or corrosion at the fuel pump module, driver module or their connectorslikely
Damaged, chafed or high-resistance wiring in the pump control or feedback circuitlikely
Worn or failing fuel pump unable to deliver the commanded outputlikely
Faulty fuel pump driver or control modulepossible
Low battery voltage or poor supply, earth or fuse and relay problems feeding the pump circuitpossible
Restricted fuel filter or blocked pump inlet strainer causing the pump to work outside its expected rangepossible
Outdated or faulty ECU software where a manufacturer bulletin identifies it as a causerare

How to diagnose

Read all stored codes and freeze frame data, noting engine load, speed, battery voltage and fuel pressure at the time the fault was set
Check battery condition and charging voltage, as low voltage can upset pump control
Inspect the fuel pump module, driver module wiring and connectors for damage, corrosion, water ingress and loose pins
Check the relevant fuses and relays and test the supply and earth under load with a multimeter
Check the control signal and feedback signal against the manufacturer's specification using a scope or suitable diagnostic equipment
Monitor commanded versus actual fuel pressure in live data during start-up and under load
Carry out a fuel pressure and volume test and check the fuel filter where one is fitted and serviceable
Check for applicable manufacturer software updates or bulletins for the specific model and engine

How to fix

Clean, repair or replace affected connectors and terminals
Repair or replace damaged wiring in the pump control or feedback circuit
Replace the fuel pump module if it fails pressure, volume or electrical tests
Replace the fuel pump driver module if the supply, earth and wiring are proven good
Replace a blocked fuel filter or restore correct battery and charging system health
Update the ECU software only if a known fault with the existing calibration is confirmed

Can I keep driving?

High severity

Avoid driving until the fault is diagnosed, as the engine may stall or lose power without warning and a failing pump can leave you stranded. If it must be moved, keep the trip very short and avoid heavy loads or busy roads.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.