P0BC8Hybrid/EV Battery Pack Cooling Fan 1 Sense Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P0BC8 compares the speed fed back by battery cooling fan 1 with what the controller commanded. GM's 2016 and 2018 hybrid tables run two checks. With the fan enabled at 11 to 89 % duty for more than 11 s, the filtered difference between commanded and reported speed must stay inside calibrated limits; large errors fail within seconds, small ones after up to 43 s. With the fan off for more than 20 s, a reported speed above 120 rpm fails in 24 of 32 samples at 250 ms. It is Type B, two trips, and waits while drive or sense circuit codes are active. A dusty or worn fan that cannot reach its speed is the usual cause; a fan turning while commanded off points to a stuck drive. The circuit cases are P0BC7, P0BC9 and P0BCA.
- What you may notice
- MIL on after two trips
- Weak airflow or unusual fan noise from the battery intake
- Reduced electric assist when the pack warms up
- Likely causes
- LikelyDust-clogged impeller, blocked intake or worn fan bearing
- PossibleFan keeps running while commanded off (stuck drive or relay)
- PossibleFan electronics reporting a wrong speed
- 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 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.