my check engine light came on when I had a tune up lift the hood and I saw sparkes
Take it back to whomever did the tune up. The sparks you're seeing is the ignition system arcing. That's what is causing the check engine light to come on. The arcing causes misfiring. Most likely the spark plug boots are not securely attached to the spark plugs. HTH. -Jim
I have a 2000 hyndia sonata and I had it coded and it said cylinder 3 is misfiring we changed plugs and it has new foil packs on it. The check engine light is on I ran sea foam through it. It has slight miss to it
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