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

P2A00

O2 Sensor Circuit Range/Performance Bank 1 Sensor 1

Long-term plausibility checks show that the front oxygen sensor on bank 1 reacts too slowly or stays too close to a fixed value. The signal does not show normal cross-counts during closed-loop operation.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / numberA / 00

Possible causes

  • Oxygen sensor aging high
  • Sensor contamination (oil, silicone) medium
  • Sensor element aged beyond calibration window low

Symptoms

  • Check engine light on
  • Increased fuel consumption
  • Possible rough idle or hesitation
  • Failed emissions test

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 120–400 €
  • Estimated time: 0.5–1.5 h
  • Component: oxygen sensor
  • Component: oxygen sensor 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