P0E12Hybrid/EV Battery Pack Coolant Heater A Control Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0E12 concerns the command circuit of battery coolant heater A, the electric element that warms the coolant sent to the hybrid or EV battery when the pack is too cold for charging or full power. The controller flags it when this circuit is open or otherwise electrically faulty. No manufacturer documents P0E12 publicly. GM's 2016 Volt shows the same check under its own code P1EC3: above 10.2 V system voltage, 20 failed readings within 40 samples taken every 100 ms set a Type B code. CARB requires every electronic output used to heat the energy store to be checked for circuit faults. Typical finds are a cracked conductor, an unseated connector or a dead output stage. In frost the car may then limit charging or rely on the engine. Shorts to ground or voltage are P0E13 and P0E14.
- What you may notice
- Check engine light on
- Slow or reduced charging in cold weather
- Engine runs more often than usual on cold days
- Reduced electric power until the pack warms up
- Likely causes
- LikelyBroken or chafed wire in the heater A command circuit
- LikelyLoose, corroded or unlocked connector at the heater or controller
- PossibleOpen circuit inside the heater A assembly
- RareFailed output driver in the controlling module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.