P0B8CHybrid/EV Battery Voltage Sense Q 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
- P0B8C is set when channel Q reports a voltage that fails the plausibility test against the other cells or the pack. On GM's 2012 two-mode trucks Q is NiMH block 17; the battery pack control module takes block 17 and block 18, multiplies each by twenty and compares with the measured pack voltage, failing beyond 70 V in 160 of 170 samples, Type B. GM's lithium-ion programs instead check that cell Q follows the average: the 2016 Volt within 7 of 8 seconds, the Cadillac ELR in 20 of 40 samples, the 2019 controllers in 35 of 40 samples with a 0.005 V trend, all Type A. Because the value itself is within limits, the driver may notice little beyond the MIL. A software update or replacement of the monitoring electronics resolves most cases.
- What you may notice
- MIL with little change in driving
- Usable battery capacity reduced
- Likely causes
- LikelyMonitoring electronics misreading channel Q
- PossibleOutdated battery controller software
- RareBlock 17 or 18 voltage deviating 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.