What it means
Fuel pump module B control voltage below expected range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
Fuel pump module B is the second pump module in systems that use more than one pump or module. The control module monitors the electrical control signal to module B and sets this code when the signal is lower than expected, often because of a short to ground or a poor connection; it does not alone prove a pump-flow problem.
Common causes
Most likely first.
- Wiring shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check engine light on
- Hard start, no start, or stalling under load
- Power loss especially at high load or rpm
- Possible long cranking time
How to diagnose it
- Review freeze-frame data and live pump-control or fuel-pressure information to see whether the low signal coincides with starting or load problems.
- Inspect module B's wiring and connector for chafing, water intrusion, corrosion, or terminals pushed back into the connector.
- Check the module B control circuit for a short to ground using the vehicle wiring diagram and the manufacturer's procedure.
- Check terminal contact, circuit continuity, and module supply or ground connections against the manufacturer's specification.
- If the external wiring passes, test module B and its control input before replacing parts.
Common fixes
- Repair wiring shorted to ground in the module B control circuit.
- Clean or repair corroded or loose module B connector terminals.
- Reseat pushed-back terminals and secure the connector.
- Replace module B only if testing confirms an internal fault.
Can I keep driving?
Avoid heavy loads and do not rely on the vehicle if it is hard to start, stalls, or loses power; the low control signal may affect fuel delivery. Stop driving if the engine stalls or cannot maintain power safely.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.