A fault code doesn’t yet mean the unit or sensor itself is faulty: often it’s the plug and connector leading to it.
Possible causes
- Diluted, dirty or wrong reductant
- Faulty AdBlue quality sensor in the tank
- False signal from a worn rear NOx sensor
What you can do yourself
- Check the AdBlue with a refractometer: normal is 32.5% (31.8–33.2%)
- If out of spec — drain, flush the tank with fresh AdBlue and fill with new AdBlue (ISO 22241)
- If this is the only code — do not replace the SCR catalyst; first a software update and diagnostics
Stop and don’t drive on if:
- The Check Engine light is flashing
- The temperature gauge is in the red or the overheating light is on
- The red oil pressure light is on
- Smoke from under the bonnet, a burning or petrol smell
- Strong jerking, knocking from the engine, or the car barely moves
The explanation comes from the error code reference in the AvtoElektrik PRO app.