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CarMD: Ignition Coils, Spark Plugs, O2 Sensors Caused Trouble in 2018

Car repair costs were up across all U.S. regions last year in CarMD’s latest Vehicle Health Index report, and ignition coils, spark plugs, and oxygen sensors tied for the lead in check engine repairs.

April 24, 2019
CarMD: Ignition Coils, Spark Plugs, O2 Sensors Caused Trouble in 2018

The average cost to repair a check engine problem increased by 11% to a national average of $381 in 2018, according to the latest figures from CarMD.

Photo courtesy CarMD

2 min to read


IRVINE, Calif. — Automotive diagnostics data and business solutions provider CarMD released its latest CarMD Vehicle Health Index, an annual report designed to provide an overview of information related to check engine-related car repairs, costs, and trends.

For the first time, analysts included parts and component rankings, reporting a three-way tie for the No. 1 most commonly diagnosed check engine light repair. “Replace ignition coil(s) and spark plug(s)” and “replace oxygen sensor” each accounted for 5.81% of repairs in 2018. U.S. vehicle owners also saw a 6.5% year-over-year increase in the average cost to repair check engine light issues, with costs up across all four U.S. regions.

“Several factors impact the type and cost of repairs, including vehicle age, driving conditions, upkeep and how often a driver addresses a dashboard warning light, which can snowball from a single faulty spark plug into the need for additional repairs if ignored,” said Ieon Chen, CEO of CarMD. “By monitoring industry trends, we hope to educate drivers about the importance of repair and maintenance. Likewise, as our data reports an increase or decrease in a particular repair, automotive service professionals can adjust their customer communication and parts inventory accordingly.”

Rounding out the five most common problems found to trigger the check engine light after ignition coil and spark plug, and O2 sensor were the catalytic converter, loose or damaged fuel cap, and ignition coil without spark plug replacement. There was a slight increase in ignition coil issues, while slightly fewer mass air flow sensor, oxygen sensor and EVAP purge control valve replacements in 2018.

Analysts found the average cost to repair a check engine problem in the U.S. in 2018 was $381, including parts ($224) and labor ($157), representing an 11% increase in labor and 3.5% uptick in parts costs. Repair costs were up across all regions of the U.S., with the West seeing the largest increase (8%) and Midwest seeing the smallest (1%).

Vehicle owners in the West paid the most for check engine-related car repairs ($387) — nearly 6% more than drivers in the Midwest, who paid the least ($366). The most common repair in the West, Midwest and Northeast was “replace oxygen sensor(s)” while it was “replace ignition coil(s) and spark plug(s)” in the South.

To read the report in its entirety, click here.

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