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

P2195

O2 Sensor Signal Stuck Lean (Bank 1, Sensor 1)

The upstream oxygen sensor on bank 1 returns a constant lean signal during conditions where rich content is expected (for example after a deceleration fuel cut-off recovery). Usually a sensor that has lost its rich-side response or a slow heater warm-up.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number1 / 95

Possible causes

  • Upstream sensor failed stuck lean high
  • Sensor heater slow to warm up medium

Symptoms

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

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 80–500 €
  • Estimated time: 0.3–2 h
  • Component: oxygen sensor upstream
  • Component: oxygen sensor heater
  • 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