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

P252A

Engine Oil Quality Sensor Circuit

General electrical fault on the engine oil quality sensor — typically a capacitive/dielectric sensor that estimates oil aging from permittivity, viscosity proxies and conductivity. With no valid reading the dynamic service-interval algorithm falls back to the fixed-interval default.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / 2A

Possible causes

  • Open or shorted wiring to the sensor high
  • Failed sensor electrode after long use medium

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 120–600 €
  • Estimated time: 0.5–2 h
  • Component: oil quality sensor
  • Component: sensor wiring

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