I have a 1995 Bmw 318i (E36) model that has been causing me lots of grief because of changing fault codes. The check engine light has been on for about a year. The most frequent code is a bad knock sensor, next a DME fault code much less often, then on the instrument panel a check brake fluid light. Never all at the same time, the codes seem to come and go. The car runs perfectly fine but I have an emissions test coming up and I don't believe they will test it with the engine light on. All thoughts needed. Help me solve this "mystery".