P2666 code meaning
Fuel Shutoff Valve B Control Circuit Low
What P2666 means
P2666 is stored when the control line of fuel shut-off valve B sits at too low a voltage, the typical sign of a short to ground between module and valve or inside the coil. Depending on how the driver is built, the valve may then open whenever the ignition is on, or the module switches the output off for protection. No manufacturer documents P2666 publicly. In bi-fuel vehicles such as GM's CNG Impala, the ECM controls normally closed cut-off valves on the gas side and changes over to gasoline as soon as it detects a problem in one fuel system; GM's Silverado and Sierra CNG models signal such errors with a rapidly flashing fuel indicator. P2665 is the open circuit and P2667 the short to voltage on the same valve, P0006 the low fault of valve A.
P2666 at a glance
- Check engine lightUsually not
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2666
- Gas mode switched off, engine runs on gasoline
- Fuel mode lamp flashes rapidly
Common causes of P2666
- Most likelyControl wire chafed through and shorted to ground
- PossibleValve coil shorted internally
- Less likelyWater ingress in the valve connector
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel shutoff valve bSolenoidWiring harness
What each part of P2666 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 6 | Area: computer (engine control module) and output circuits. |
| 66 | The exact fault in that area. |
What to do next
- Note P2666 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2666
What does P2666 mean?
P2666 means "Fuel Shutoff Valve B Control Circuit Low". P2666 is stored when the control line of fuel shut-off valve B sits at too low a voltage, the typical sign of a short to ground between module and valve or inside the coil. It is a generic code, so it means the same on every make.
Is it safe to drive with P2666?
Drive gently and only to a workshop. With P2666 the car can go into limp mode (reduced power) to protect itself.
Will P2666 fail an emissions test?
Yes, it can. P2666 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2666 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will P2666 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.