Q: Can't pass smog check due to Check Engine light.

asked by on January 11, 2016

Check Engine light is on and I cannot pass a smog check. The mechanic said it might be electrical and couldn't help me.

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In your case I would recommend getting a second opinion. Enlist the help of a professional, such as one from YourMechanic, to scan your vehicle for trouble codes. The check engine light and the smog test failure are certainly related. The check engine light did not exist until the emissions stuff came to be put on engines. The only reason the check engine light comes on is to inform you that your engine is producing higher emissions, but because of this it may also not run as well due to how the emissions parts are installed on the engine. After the trouble codes are pulled, a more accurate diagnosis can be given.

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