Powertrain, generic (extended)

P2BB7 Engine Coolant Temperature Sensor 6 Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

With P2BB7 the sixth coolant sensor delivers an electrically valid value that nevertheless makes no sense. Plausibility tests of this kind compare the sensor with the other engine temperatures after a long cold soak, expect a clear rise once the engine warms up, and flag a value that never moves. CARB requires such rationality monitoring for coolant temperature inputs on which emission functions depend. No manufacturer publishes a set condition for P2BB7; GM, whose 2019 and 2025 engine tables do read a sixth coolant input, lists only the electrical codes P2BB8, P2BB9 and P2BBA for it. Possible reasons are a drifting element, a sensor sitting in a branch without flow because a pump or valve has failed, or contact resistance. Pure circuit faults are P2BB6, P2BB8 and P2BB9.

Likely causes

Sensor 6 element drifted out of its characteristic curve
No coolant flow at sensor 6 due to failed pump, valve or air pocket
Contact resistance at connector or terminals

Symptoms

  • MIL on, usually only after a cold start and warm-up
  • Sensor 6 value lags or stays flat compared with the other coolant sensors

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–500
Time0.5–3 h

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

Parts involved

engine coolant temperature sensor 6wiring harnessecm

Related codes

P2BB6P2BB8P2BB9P2BBAP2B2CP2AFD

References: law.cornell.edu, gsi.ext.gm.com.