P2666: Fuel Shutoff Valve B Control Circuit Low
What to do
The vehicle will run on its other fuel, so you are not stranded. The gas supply will be shut off and stay shut off, which is the safe state rather than a dangerous one.
Ask for the wiring to be traced before the valve is replaced. The cable to a gas tank runs under the floor of the vehicle, through road salt, water and stone damage, with metal all around it — so a rubbed-through wire there is far more likely than a failed valve, and much cheaper to put right. Reaching the valve itself means depressurising the tank first.
Use an installer qualified on gas systems rather than a general garage.
What this code means
The second fuel shutoff valve's control circuit reads below its valid range — normally a short to ground, or a module output that has failed low.
What the valve is and why it fails closed rather than open is set out at P2665.
The wiring's route is what makes a short to ground the likely finding. A gas system's tank sits where a tank can be put — under the floor, in the boot well, or where the spare wheel used to live — so its cabling runs along the underside of the vehicle or through the floor to reach it. That is the harshest environment on any vehicle for a loom: road salt, water, stone impact and a metal floor pan a few millimetres away in every direction.
So damage is usually mechanical and locatable rather than a component failure, and following the loom is a better first move than condemning a valve that requires a pressurised tank to be depressurised before it can even be reached.
The vehicle continues on its other fuel.
Likely causes
Start here
- Wiring shorted to ground · moderate
- Damaged wiring harness · moderate
- Corroded or loose connector · easy
Less common
- Failed fuel shutoff valve · specialist
- Control module driver failure · specialist
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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