BMW Questions? Ask a BMW Repair Expert for Answers.
it is possible that CATs could be bad, but not terribly likely
more likely than a bad cat would be a lean fuel mixture causing the high NO
what sets a code or warning light vs. what a smog check considers out of spec are totally different, so the fact there are no codes stored should not have been a surprise to the smog guy. If there were codes you would fail automatically immediately. The purse of the actual exhaust monitoring part of a smog test is to find excess emissions that do not set codes.
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