P0AFBHybrid/EV Battery System Voltage High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0AFB guards against overcharging: the pack voltage, or a single cell, exceeds a temperature-dependent upper limit. GM's 2016 and 2019 tables use 320 of 400 samples (about 10 s) for the pack and 112 of 140 for a cell, Type A, and latch the code until a technician clears it by command; the 2011 Volt table also uses Type A. On the 2007-09 Saturn Vue Hybrid, GM's PIP4005A finds P0AFB together with P0AF8 caused by a loose negative battery cable. Mercedes-Benz uses P0AFB00 on 48 V starter-alternator systems for an on-board voltage that is too high, with software fixes for M256 engines, S-Class and GLE/GLS. Toyota's Prius Prime tech tip uses P0AFB11 with a current sensor text.
- What you may notice
- Hybrid system or MIL warning
- Start-stop or regenerative braking disabled
- Possible no crank on mild hybrids
- Likely causes
- PossibleLoose or arcing battery cable causing voltage spikes
- PossibleControl unit software allows overvoltage (Mercedes 48 V bulletins)
- PossibleCell imbalance so that one cell overcharges
- RareFaulty voltage sensing reporting too high a value
- 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: €100 – €6,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.