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Forum > Failed Smog Test > Question

Does a car automatically fail if the check engine light is on? I own a 2002 Mazda Millenia.

My check engine light comes on and off and I have been to the dealer and they said it could be my catalytic converter but it hasn't completely gone bad. If my check engine light is on will they automatically fail me for the test. My car gives me no problems, does not smoke, and the light goes on and off. I will need to get my smog check soon.
Answer:

Any time your Mazda Millenia's check engine light illuminates it is cause for concern, and will cause a smog check failure... Even if the light is not on at the time of the smog check. The fact that the light was on (recently) will force the OBDII emissions computer (which your 2002 Mazda is equipped with) to transmit information to the smog machine indicating the check engine light was on and there are trouble codes stored. Very often you may not notice an engine problem, but this is only because your engine's computer is operating under pre-programmed information rather then of real-time. In other words the problem still exists but your engine learns to live with it. Our recommendation is you have a certified smog repair shop conduct a full system diagnosis. As we mentioned above, along with the "Check Engine" light being illuminated, there are stored computer codes in the engine control computer which the smog station will be able to retrieve and use for diagnosing purposes. These codes more then often will direct the smog technician to the fault which is causing the smog check failure. posted by SmogTips Support

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