BMW Repair: Emmission Failure, 1997 bmw 328i, emmission test

Question
My 1997 BMW 328i failed the GA emmission test because the check engine light was on. It's been on for 6 months and my local mechanic can't find anything wrong with it. He resets but the light comes back on. The codes given were P1421 & P1423 but no one can tell me what they mean. I've found a couple of web sites but those codes are skipped.
Can you tell me what they mean and how to fix the problem?
Thank you, Pat Spivey


Answer
i don't know what those codes are. the 1st problem is the check engine light, the 2nd problem is your mechanic. you need to go to a dealer so they can diagnose it correctly. the light is coming back on because there is a problem resetting the light doesn't make the problem go away. I am willing to guess that you have a faulty oxygen sensor and that is causing your car to fail emissions