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

P2431

Secondary Air Injection System Air Flow/Pressure Sensor Circuit

The ECU detects a general fault in the secondary air injection system air flow or pressure sensor circuit. The diagnostic cannot verify proper SAI operation.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number4 / 31

Possible causes

  • Defective SAI sensor high
  • SAI sensor wiring fault medium

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 120–500 €
  • Estimated time: 0.5–2 h
  • Component: sai pressure sensor
  • Component: sai wiring
  • 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