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

P2A40

Alternative Fuel System - Injector Leakage to Rail Detected

The AFCM detects pressure decay in the alternative fuel rail consistent with injector leakage. Even with all injectors commanded closed, fuel flows back into the rail.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / numberA / 40

Possible causes

  • Injector seat worn - leaks closed high
  • Injector seal aged - external leak path medium

Inspection / repair

  • Difficulty: hard
  • DIY: shop recommended
  • Estimated cost: 400–2200 €
  • Estimated time: 2–8 h
  • Component: alt fuel injectors
  • Component: alt fuel rail
  • MIL / check engine light
  • emissions-relevant
  • 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