OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

P0AFB

Hybrid/EV Battery System Voltage High

The HV battery system voltage exceeds the expected window. Charging overvoltage or sense fault. Cell-group voltage monitoring is the foundation of HV battery safety — drift here triggers contactor opening, charge inhibit, and reduced power to protect the pack.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / numberA / FB

Possible causes

  • Cell imbalance high
  • Sense circuit fault medium
  • Ground point with elevated resistance low

Symptoms

  • EV/hybrid system warning light on
  • Reduced power output or limp mode
  • Charging may fail or be slowed
  • Reduced electric range

Inspection / repair

  • Difficulty: hard
  • DIY: shop recommended
  • Estimated cost: 500–5000 €
  • Estimated time: 3–16 h
  • Component: hv battery
  • Component: bms
  • MIL / check engine light
  • limp mode possible

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication