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Q: Can't pass smog check with Check Engine Light on

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The Check Engine Light keeps coming on, preventing me from passing a smog check. I replaced the compression sensor already.

The most common reason for your Check Engine Light coming on is for random engine misfires. You may be having this problem, and may need to have the ignition diagnosed, to see what is causing the misfire. You may have a failure of your coils, or plugs. The Check Engine Light would need to be checked to see which codes are received, for a proper diagnosis.

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