P0BC0Hybrid/EV Battery Pack Cooling Fan Supply Voltage Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0BC0 reports that the voltage feeding the battery cooling fan is lower than expected while the fan is switched on. A short to ground downstream of the fuse, a corroded connector or a relay with burnt contacts drops the voltage, so the fan turns slowly or not at all. No manufacturer documents this exact code publicly. Toyota's hybrid controller measures the fan supply on the auxiliary battery side and raises the duty when it is low, which shows why a sagging feed matters for cooling. CARB asks for circuit monitoring of all battery thermal management parts. The open case is P0BBF, the high case P0BC1 (GM: welded relay). A weak 12 V battery can cause a sag too, so check it first. Expect reduced power when the pack heats up.
- What you may notice
- Hybrid system warning or MIL on
- Battery fan runs slowly or noticeably weaker
- Reduced electric assist when the pack is warm
- Likely causes
- PossibleFan supply wire chafed and shorted to ground
- PossibleBurnt fan relay contacts or corroded terminals causing voltage drop
- PossibleWeak 12 V auxiliary battery or poor ground
- RareSeizing fan motor pulling excessive current
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €20 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.