P2634
Fuel Pump B Control Circuit High
Fuel pump control
Generic OBD-II
High
What it means
P2634 means the ECM detected high voltage in the control circuit for fuel pump B, typically a short to power or a relay/driver fault. Because this circuit runs a fuel pump, a fault can interrupt fuel delivery — leading to hard starting, stalling, or power loss — so it's worth diagnosing quickly.
High
Can I keep driving? May crank-no-start, stall, or lose power under load if fuel delivery is affected — diagnose before relying on the car.
Common symptoms
What you'll notice
- Check-engine light on with the code stored
- Hard starting, extended cranking, or no-start
- Stalling or loss of power under load
- Fuel pump not running or running erratically
Common causes
Most likely first
- Short to voltage in the fuel pump B control wiringLikely
- Faulty fuel pump relay, driver module, or control moduleCommon
- Corroded or loose connector on the control circuitCommon
- Faulty ECM control-circuit outputLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data to see when the fault set.
- Inspect the pump control wiring and connectors for a short to power.
- Test the fuel pump relay/driver module operation.
- Check fuel pressure and confirm the pump runs on command.
- Replace the faulty relay, driver, or pump as diagnosed. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P2634?+
Risky. A fuel-pump control fault can cut fuel delivery and leave you stalled or unable to restart. Diagnose it before depending on the vehicle.
Can I just clear P2634?+
It returns until the circuit fault is fixed. Clearing won't restore reliable fuel delivery.
Related codes
Often seen with P2634
Read & clear P2634 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX