The average cost to address a check engine light climbed to a record $554 in 2025, up 33% from the year before, according to CarMD’s 2026 Vehicle Health Index. The report, released in April 2026 and built on repair data from 2025, found that a catalytic converter replacement now averages $1,511, nearly three times the cost of the typical check engine repair.
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Labor drove much of the increase. CarMD put labor costs up 51% from the prior year as procedures became more time-intensive and vehicle systems more complex, while parts costs rose 23% on material pricing, multi-component repairs and some imported components passed along as tariffs. The average vehicle on U.S. roads is now 12.8 years old, an all-time high.
The Ten Most Common Warning-Light Repairs
CarPro’s summary of the report lists the ten most common dashboard warning light repairs of 2025 with their average costs: the catalytic converter at $1,511, the oxygen sensor at $287, ignition coil and spark plugs together at $480, mass air flow sensor replacement at $346, ignition coil alone at $256, the EVAP canister purge control valve at $172, fuel injectors at $572, the ABS wheel speed sensor at $314, the thermostat at $324 and spark plugs at $299. The CarPro write-up of the annual CarMD report headlines the catalytic converter as the top item. The ten repairs span a wide range, from $172 for the EVAP canister purge control valve at the low end to the $1,511 converter at the high end, so the single $554 average masks both inexpensive sensor swaps and four-figure emissions-component replacements that pull the mean upward.
The ABS wheel speed sensor is a first-time entry in the national top ten, a sign that safety-related alerts are rising, and tire pressure monitoring sensors remain among the most frequent repairs. CarMD also added a section on van life, covering the Mercedes Sprinter, Ram ProMaster and Ford Transit, and says those Class B RVs face more frequent and more expensive repairs than typical passenger vehicles, with more turbo and diesel issues and higher transmission failure rates.
Why One Warning Light Becomes Several Repairs
The ranking is a reminder of how uneven the bills are, since seven of the ten repairs cost under $350 while one costs $1,511.
CarMD says many issues are interconnected: misfires or a faulty oxygen sensor can eventually damage the catalytic converter, which turns a modest sensor or ignition repair into the most expensive fix on the list. Ignoring a failing oxygen sensor can also cut fuel economy by as much as 40%, according to CarMD, so a delay can raise running costs before it raises the repair bill.
David Rich, CarMD’s vice president of automotive technology, said that keeping up with routine maintenance and addressing dashboard warning lights early is a simple way to keep a vehicle running safely and efficiently as it ages. He added that even small issues can reduce fuel economy, which drivers are watching closely as gas prices rise.
Earlier CarMD Editions Show the Climb
The record is easier to appreciate against the index’s history. In the 2017 edition, covered by Automotive Fleet, repair costs tied to check engine lights rose 2.7% on 2016 data, and a catalytic converter averaged $1,190, an oxygen sensor $258 and a mass air flow sensor $378. Against those figures, the 2025 catalytic converter average of $1,511 is up about 27%, and the oxygen sensor average of $287 is up about 11%.
The index began as a manufacturer ranking, and its methodology rests on diagnostic trouble code data rather than surveys. A report on the first annual edition described CarMD.com Corporation’s score as combining the share of vehicles with check engine problems and the average repair cost per vehicle, with Toyota, including Lexus and Scion, ranked first at 0.67 for the year ending October 1, 2011.
The year-to-year path has not been a straight line. An S&P Global item on the 2025 index, dated April 23, 2025, carried a headline saying check engine repair costs were down slightly, and an earlier item from April 2024 reported that repair costs had risen and that nearly half of drivers had a dashboard warning light on. Both stories sit behind a paywall, so their dollar figures are not reproduced here, but the sequence of headlines shows that annual changes in the index can run in either direction before the 2025 data pushed the average to its record.
With labor up 51%, parts up 23% and the average vehicle at a record 12.8 years old, the 2025 jump to $554 reflects several cost pressures arriving together. The practical lesson from CarMD’s data is that a lit warning lamp is cheapest to address immediately, before a cheap sensor failure cascades into a four-figure catalytic converter replacement.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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