P2B2BEngine Coolant Temperature Sensor 5 Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- Engines with split cooling, electric pumps or separate head, block, radiator and heater branches can carry five or more coolant sensors; the numbering is the maker's choice. P2B2B is the generic circuit code for number 5, meant for controllers that do not separate low from high. No manufacturer documents a set condition for P2B2B publicly. GM does use a fifth coolant sensor input, for instance in its 2019 tables for the 2.7 L L3B and in its 2025 engine tables, but reports its circuit faults only as P2B2D and P2B2E. NTN-SNR lists P2B2B as an electrical fault in the sensor 5 circuit, and CARB requires coolant temperature inputs to be monitored for opens and for readings outside their range. Typical reasons are a loose plug, a broken lead or a failed NTC element.
- What you may notice
- MIL with stored code
- Cooling fans or thermal management running on default values
- Likely causes
- LikelyLoose connector or broken lead at sensor 5
- PossibleFailed NTC element in sensor 5
- RareFaulty sensor input in the engine control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €30 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.