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
- The NOx trap is worn out or poisoned by sulphur
- NOx sensor or downstream O2 sensor
- Exhaust leak ahead of the sensor
- High-sulphur fuel or oil without the right approval
What you can do yourself
- This catalyst is fitted to some diesels and direct-injection petrol engines: it stores NOx and cleans itself from time to time, when the engine briefly runs rich.
- Refuel at trusted stations and use oil with the approval listed in the manual: sulphur and ash ruin the catalyst.
- Usually doesn’t affect how the car drives.
The explanation comes from the error code reference in the AvtoElektrik PRO app.