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1995 Cadillac Deville smog check. Smog tech says it's running too rich.

My smog technician says my car will not pass a smog because it is running rich. What does that mean and does it have anything to do with the oxygen sensor?
Answer:

Your 1995 Cadillac Deville running rich means that too much fuel is getting into the combustion chambers, and it more then likely has to do with the oxygen sensors. A smog check repair station will have to find out why your Cadillac Deville is running rich and probably producing high CO. The diagnosis for this fault should begin with inspection of the fuel injection "feedback" system. This includes ensuring the oxygen sensor is working properly, your Cadillac's emissions computer is receiving the signals from the oxygen sensor, the computer is computing the data properly and sending the correct signals to the fuel injectors to either increase or decrease fuel delivery to the combustion chambers. At the end of the feedback test it will be know whether the high CO fault is electronic or mechanical, and the technician can further diagnose the fault. Your Cadillac Deville's smog check failure diagnosis should also include inspecting for high fuel pressure, air restrictions (i.e. dirty air filter) and leaking fuel injectors. A dirty air filter may restrict ample air from entering the combustion chambers. Any condition which could cause a lack of air getting to your Deville's intake manifold will create a rich fuel condition and result in high CO. posted by SmogTips Support

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