P2B20Hybrid/EV Electronics Coolant Temperature Sensor B Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Sensor B is a second temperature sensor in the coolant loop that serves the hybrid or EV power electronics, such as inverter, DC/DC converter or on-board charger; where it sits relative to sensor A is up to the vehicle maker. P2B20 is the undifferentiated circuit code: the controller finds the signal unusable without deciding between low and high. No manufacturer documents P2B20 publicly. Supplier NTN-SNR lists it in its coolant sensor catalogue as an electrical fault in the sensor B circuit, and CARB requires every input of inverter thermal management to be checked for circuit faults. GM's handling of sensor A (P0CF0/P0CF1 in its 2019 HPC2 table) shows the usual NTC logic behind such checks. Without the reading, the system tends to cut inverter and charging power.
- What you may notice
- Hybrid or EV system warning and stored fault code
- Reduced drive or charging power as a precaution
- Electronics coolant pump running more often or at higher speed
- Likely causes
- LikelyLoose connector, corroded pins or broken wire in the sensor B circuit
- PossibleSensor B element open or shorted internally
- RareFaulty input stage or reference supply in the controlling module
- 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: €40 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.