P027D
Fuel Pump Module B Control Circuit High.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 2
- AreaFuel and air metering (injector circuit)
- 7D
- FaultThe specific fault in that area
What it means
P027D means the engine or fuel pump control module has detected a voltage on the control circuit of fuel pump module B that is higher than it expected. Module B is the second fuel pump or pump driver, and which one that is depends on the vehicle. The control unit compares the commanded signal with the voltage it measures on the circuit. If the two do not match, it sets the code and may limit fuel delivery.
Symptoms
- Engine warning light on
- Long cranking or hard starting
- Hesitation or loss of power under load
- Engine cutting out or stalling
- Reduced performance or limp mode
- Low fuel pressure or fuel pressure-related codes stored alongside
Possible causes
- Control wire for fuel pump module B shorted to a voltage supply, or chafed against another live wirelikely
- Corroded, damaged or loose connector at the pump module, control module or in-line pluglikely
- High resistance or open circuit on the pump ground or control return, which pushes the measured voltage highpossible
- Faulty fuel pump module B with an internal electrical fault or failing driver electronicspossible
- Faulty fuel pump control module or internal driver fault in the engine control unitpossible
- Low battery voltage or charging system fault upsetting the pump control signalrare
How to diagnose
- Read all stored and pending codes and the freeze frame data. Note any fuel pressure, battery voltage or other fuel pump codes, then check for any manufacturer service information that applies to the model and engine.
- Check battery condition and charging voltage, since low or unstable voltage can cause circuit faults.
- Inspect the wiring and connectors for fuel pump module B and the control module. Look for chafing, heat damage, water ingress, corrosion and pushed-back pins. The route depends on the model, so use the wiring diagram.
- Check the relevant fuses and relays and the power and ground supplies to the pump module.
- With the ignition on, measure the voltage on the control circuit, then compare it with the specification for that vehicle. Also test the pump ground for voltage drop.
- Test the control wire for a short to voltage and for an open circuit, with the connectors disconnected at both ends and the battery safely isolated as the procedure requires.
- Use a scan tool that can command the pump and watch fuel pressure and the commanded duty. Check that the pump responds and that the pressure follows the command.
- If the wiring and supplies are good, test or substitute the pump module or control module as the manufacturer's procedure directs.
How to fix
- Repair or replace the damaged wire that is shorted to voltage, and secure it away from the source of chafing.
- Clean, repair or replace corroded or damaged connectors and terminals.
- Restore any faulty power or ground supply, and repair the high-resistance connection.
- Replace fuel pump module B if testing shows an internal fault.
- Repair or replace the fuel pump control module or engine control unit if the driver circuit is faulty, then code or program it as the manufacturer requires.
- Fix any charging or battery fault, then clear the code and road test to confirm it does not return.
Can I keep driving?
The car may run on reduced fuel supply, but it could lose power or stall without warning, so avoid driving it far and get it checked soon. Stop driving it if it starts stalling, cutting out or going into limp mode.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.