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

P2173

High Airflow/Vacuum Leak Detected (Slow Accumulation)

Long-term fuel and air adaptation values indicate a slow but continuous excess of air entering the engine. The ECU concludes that an unmetered air leak is gradually growing in the intake system.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number1 / 73

Possible causes

  • Cracked vacuum hose or intake gasket high
  • Dirty mass airflow sensor medium

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 50–400 €
  • Estimated time: 0.5–2.5 h
  • Component: intake manifold gasket
  • Component: vacuum hoses
  • Component: throttle body
  • Component: mass air flow sensor
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required

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