P2666
Fuel Shutoff Valve B Control Circuit Low
Fuel delivery (shutoff valve)
Generic OBD-II
Medium
What it means
P2666 means the control module has detected low voltage (typically a short to ground) in the fuel shutoff valve 'B' control circuit. This valve can cut fuel flow, so depending on the fault the engine may stall or fail to start — though in many cases the main sign is just the stored code. It's worth diagnosing before depending on the vehicle.
Medium
Can I keep driving? Often drivable, but a fuel shutoff valve fault can cause stalling or a no-start, so have it diagnosed before relying on the vehicle.
Common symptoms
What you'll notice
- Check-engine light on
- Possible stalling or hard starting
- Engine may fail to start if the valve stays shut
- Sometimes no obvious symptom beyond the stored code
Common causes
Most likely first
- Short to ground in the fuel shutoff valve 'B' control circuitLikely
- Open, damaged, or corroded wiring or connector at the valveCommon
- Faulty fuel shutoff valveCommon
- Poor ground or a fault in the control module driving the circuitLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and inspect the shutoff valve wiring and connector for a short to ground, damage, or corrosion.
- Check the control circuit voltage against spec while the valve is commanded.
- Test the valve's resistance and operation; repair wiring or replace the valve as needed.
- Clear the code and confirm the engine starts and runs normally on re-test.
FAQ
Quick answers
Is it safe to drive with P2666?+
Be cautious — depending on the valve's state, the engine could stall or fail to restart. Have it checked before longer trips.
Can I just clear P2666?+
It will return until the circuit fault or valve problem is repaired, and clearing it doesn't reduce the risk of a stall or no-start.
Related codes
Often seen with P2666
Read & clear P2666 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