What it means
Open circuit at fuel pump module B (second pump module on dual-tank or high-output fuel systems).
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 its control circuit and sets this code when the circuit is open, interrupting communication or control of module B; the code alone does not establish that the pump itself has failed.
Common causes
Most likely first.
- Wiring break
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
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
- Check freeze-frame data and related fuel-pressure or pump-control codes to see whether the fault coincides with hard starting, stalling, or load.
- Locate module B using vehicle-specific service information and inspect its connector and harness for breaks, loose plugs, or pushed-back pins.
- Check the module B control circuit for continuity and an open using the wiring diagram and the manufacturer's procedure.
- Inspect connector terminals and module grounds or supply connections for poor contact, and compare circuit readings with the manufacturer's specification.
- If the external circuit checks out, test module B and its control input according to the vehicle's service information.
Common fixes
- Reconnect and secure a loose module B connector.
- Repair a broken wire or poor terminal connection in the module B control circuit.
- Repair a damaged connector or ground connection.
- Replace module B only if circuit testing confirms an internal fault.
Can I keep driving?
Avoid driving if the vehicle is hard to start, stalls, or loses power, especially in traffic; an open module B circuit can interrupt fuel delivery. Arrange a repair before relying on the vehicle.
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.