I have a 99 Mustang. About a year or so ago, my check engine light (hereby known as the CEL) went on. I took it to my local shop, who charged my $75 and said they fixed it. 2 days later, it comes back ...

Check-engine lights, also known as Malfunction Indicator Lamps (MIL), appear for a reason-specifically when an engine is operating outside of its normal emissions parameters. When that light flashes, ...