P0E21Hybrid/EV Battery Pack Coolant Control Valve B Control Circuit Driver Current/Temperature Too High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0E21 is the overload or overheat report of the driver for coolant control valve B. No manufacturer documents P0E21 publicly. What B means differs between makers: on the 2011 Chevrolet Volt, GM's own codes for valve B (P1EC7, P1EC8) actually watch the second drive line of the same valve motor that serves as valve A, whereas other layouts have a physically separate second valve for a chiller or radiator branch. For diagnosis it is therefore worth checking first which actuator the maker calls B. The protection itself works like that of TI's integrated high-side switches for cars, which cut off at their current limit or near 150 °C and report it. CARB obliges makers to monitor these outputs electrically. Electrical circuit faults of valve B are P0D1A, P0D1D and P0D1E.
- What you may notice
- Check engine light on
- Coolant routing does not change as commanded
- Battery temperature drifts, power or charging limited
- Likely causes
- LikelyValve B binding so its actuator stalls against the stop
- PossibleShort or low resistance in the valve B actuator or harness
- RareDegraded driver stage in the control 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: €100 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.