P2BD9Motor Electronics Coolant Temperature Sensor B Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2BD9 means coolant temperature sensor B in the motor electronics loop delivers a voltage inside its electrical window, yet the temperature it reports does not fit the rest of the vehicle. The circuit itself is intact; a drifting thermistor, a sensor sitting in an air pocket or a value that stays frozen are typical. No manufacturer documents P2BD9 publicly. GM's method for sensor A on the 2013 Two-Mode hybrid trucks, P0A01, shows the principle: after the vehicle has rested for over 28,800 s, the loop temperature at power-up may differ from engine coolant temperature by no more than 30 °C, provided engine coolant and intake air agree within 15.75 °C; a failure counts as Type B. Voltages outside the window for this sensor are reported as P2BDA and P2BDB; sensor C has its own check, P2BDD.
- What you may notice
- Check engine light, usually without a noticeable driving issue at first
- Cooling fan or electronics pump running at unexpected times
- Occasional power limitation on hot days
- Likely causes
- LikelySensor B thermistor drifted out of its characteristic
- PossibleAir pocket or low coolant leaving sensor B partly dry
- PossibleAdded resistance from corroded terminals shifting the reading
- RareWrong value from a comparison sensor such as engine coolant or intake air temperature
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.