P0BC1Hybrid/EV Battery Pack Cooling Fan Supply Voltage Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P0BC1 flags voltage on the battery fan feed when there should be none, or more than expected. GM documents it for the battery pack control module of its Two-Mode hybrid SUVs and pickups (Tahoe, Yukon, Escalade, Silverado, Sierra; 2012 and 2013 tables) as a welded fan relay: with the fan commanded off, a fan monitor voltage of at least 0.9 V in 10 of 20 samples at 100 ms sets it, provided the 12 V system is between 9 and 18 V and no fan circuit code (P0A81) is active. It is Type B, MIL after two trips. A stuck relay keeps the fan running with the vehicle off and drains the 12 V battery. The open and low cases are P0BBF and P0BC0; a fan that keeps turning without this fault is P0A83.
- What you may notice
- MIL on after two trips
- Battery fan keeps running after the vehicle is switched off
- Discharged 12 V battery after standing
- Likely causes
- LikelyFan relay contacts welded closed
- PossibleFan feed shorted to a constant battery voltage wire
- RareRelay control output in the module stuck on
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €15 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.