P0B91Hybrid/EV Battery Voltage Sense R Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Here the wiring of sense R is intact, but its value does not behave like a real cell. GM's 2019 hybrid powertrain processor demands that cell R moves at least 0.005 V in the same direction whenever the cell average shifts by more than 0.022 V; 35 failures out of 40 samples at 100 ms give a Type A fault. The 2016 Volt allows 7 s of failure in an 8 s window, the ELR 20 of 40 samples at 200 ms. On the 2012 two-mode trucks R is nickel-metal hydride block 18: blocks 18 and 19 are each multiplied by twenty, and if both estimates miss the pack voltage by more than 70 V in 160 of 170 samples, P0B91 is set as Type B. A frozen measuring channel or controller software is the usual suspect.
- What you may notice
- MIL on, vehicle often drives normally
- Less electric assist or regenerative braking
- Likely causes
- LikelyMeasuring channel R reporting a stuck value
- PossibleOutdated battery controller or hybrid processor software
- RareBlock 18 or 19 voltage drifting on two-mode NiMH packs
- 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.