P0B85Hybrid/EV Battery Voltage Sense O Circuit Intermittent/Erratic
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0B85 would mark a channel O signal that is present but unsteady, with spikes or brief gaps. No manufacturer documents this code publicly; even GM, whose public tables cover channel O in detail from 2011 onward, defines only the open, rationality, low and high tests for it. The requirement behind the code family comes from CARB 1968.2: voltage sensors of a hybrid energy storage system must be monitored like other electronic components, with fault codes that identify the part to replace. A plausible cause for such a signal is a contact resistance that changes with movement, heat or moisture, typically at the cell tap, the busbar screw or the connector of the sense harness. A fault that vanishes and returns calls for wiggle testing with live data.
- What you may notice
- Warning that comes and goes
- Short-term power reduction during driving
- Likely causes
- LikelyLoose busbar screw changing contact resistance at tap O
- PossibleMoisture or corrosion in the sense harness connector
- RareCracked joint on the monitoring board
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €80 – €5,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.