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

P2257

Secondary Air Injection System Control A Circuit Low

The control circuit of the secondary air injection system A reads a voltage below specification. Either the relay output is shorted to ground or the wiring/load is faulty.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number2 / 57

Possible causes

  • Control wire shorted to ground high
  • Faulty SAI relay medium
  • Connector pins corroded - high contact resistance low

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 120–600 €
  • Estimated time: 0.5–2 h
  • Component: secondary air pump
  • Component: sai relay
  • 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