P2BB6Engine Coolant Temperature Sensor 6 Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2BB6 is the general circuit code for a sixth coolant temperature sensor, intended for control units that only know that the circuit is faulty and do not distinguish a grounded from an open or shorted-high line. Six or more coolant sensors appear on engines with split cooling, rotary coolant valves or separate branches for head, block, radiator and heater; which physical sensor gets number 6 is the manufacturer's decision. No manufacturer documents P2BB6 publicly. GM does read a sixth coolant channel in its 2019 and 2025 ECM tables, but reports its faults only through the specific codes P2BB8 and P2BB9. Under CARB rules each coolant temperature input must be tested for broken circuits and for readings beyond its plausible span. Unplugged connectors and broken leads are the likely reasons.
- What you may notice
- MIL on
- Sensor 6 shows a fixed substitute or implausible value
- Fans may run continuously as a precaution
- Likely causes
- LikelySensor 6 connector unplugged, damaged or corroded
- PossibleOpen or shorted wire between sensor 6 and the ECM
- PossibleFailed NTC element in sensor 6
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €350
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.