CarMD’s latest study looks at the most common check-engine light repairs and their average costs over the previous calendar year, then ranks the results.

The most frequent “check engine light” fix noted in a recent report is to replace the catalytic converter, which costs an average $1,313. It should come as no surprise to anyone who’s been ...

"The check engine light is designed to come on when a vehicle's on-board diagnostic system sees a problem that impacts emissions or drivetrain issues," said David Rich, CarMD technical vice president.

"The check engine light is designed to come on when a vehicle's computer sees a problem that impacts emissions or drivetrain issues, which can lead to poor performance and reduced fuel economy.

Connecticut takes the top spot from California this year as the state with the highest average check engine light repair cost ($418.37).