Powertrain, generic (extended)

P2666 Fuel Shutoff Valve B Control Circuit Low

Check engine lightUsually off
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Control wire chafed through and shorted to ground
Valve coil shorted internally
Water ingress in the valve connector

Symptoms

  • Gas mode switched off, engine runs on gasoline
  • Fuel mode lamp flashes rapidly

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–500
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel shutoff valve bsolenoidwiring harness

Related codes

P2665P2667P0006

References: static.nhtsa.gov, gmc.com, law.cornell.edu.