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

P0AD4

Hybrid/EV Battery Pack Air Flow System Insufficient Air Flow

The BMS detects that air flow through the HV battery pack is below the calibrated minimum. Cooling effectiveness reduced.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / numberA / D4

Possible causes

  • Air filter clogged high
  • Cooling fan underspeed medium
  • Pack cell imbalance approaching service threshold 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: medium
  • DIY: possible
  • Estimated cost: 80–500 €
  • Estimated time: 0.5–3 h
  • Component: hv battery pack air flow system
  • Component: hv battery cooling fans
  • 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