I took my car to take a emission test 2 days ago. It failed horribly. I tried to look online what could be causing these problems but haven't found anything yet. Can anybody Help me? I have a very high reading of NOx. I'll try and post my test later on but can anybody give me an answer as to why my 93 325is is giving out these high level of NOx. Thanks to all reply. Your help is needed and appreciated.