P2D2BHybrid/EV Battery Pack Coolant Temperature Sensor A/B Correlation
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- Liquid-cooled traction batteries often have coolant sensors at pack inlet and outlet. When the pack has rested long enough, sensors A and B should agree; P2D2B records a gap beyond the limit without naming the faulty one. No manufacturer documents P2D2B publicly. GM's 2019 hybrid tables test the pack inlet sensor alone under P0C43: after all high-voltage contactors have been open for at least 14,400 s, it fails only when it is off from both references, by 23 °C or more from the average cell temperature and by 22 °C or more from outside air, Type B. California asks for monitoring of every input used for battery thermal management. A wrong reading can make heating or chilling of the pack misjudge, limiting charging or power.
- What you may notice
- Hybrid or EV battery warning
- Reduced charging power or range
- Battery heater or chiller running unexpectedly
- Likely causes
- LikelyOne pack coolant sensor has drifted
- PossibleCorroded or loose connector at a sensor
- PossibleAir trapped in the battery coolant loop after service
- RareFaulty measuring input in the battery control module
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.