Possible causes of fault
- Urea/water mixture quality deficient, misfuelling, SCR active tank empty
- Nitrogen oxide sensors faulty (poisoned, sensor drift)
- SCR catalytic converter faulty (not enough nitrogen oxide is converted)
- Metering module faulty (too little urea/water mixture metered in)
- SCR tank system faulty (too little urea/water mixture metered in, system pressure in the metering line is too low)