P252B

What it means

The oil quality sensor is electrically intact, but the readings do not match the model — for example permittivity that does not change after an oil change, or shifts inconsistent with km/h driven. Often a contaminated electrode or oil that does not fit the sensor calibration.

Is it safe to drive?

The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.

Most likely causes

• Contaminated sensor electrode

  high

  One of the most commonly reported causes for this code — check this first.

• Oil grade outside the sensor calibration range

  medium

  A plausible cause — test and verify before replacing parts.

• Sensor element aged beyond calibration window

  low

  Less common, but worth ruling out after the more likely causes.

Related help

• Full P252B diagnosis, causes & costs
• How to read check engine light codes
• Is it safe to drive with the light on?