Study breaks down 10 most common check engine light-related repairs in 2024 and their average repair costs, including parts and labor
Irvine, Calif.—A new report finds that U.S. car repair costs were down 3% in calendar year 2024 with a slight increase in average labor costs and flattening in parts costs. The findings were published by CarMD in its 2025 CarMD Vehicle Health Index, an annual study of check engine light-related car repair trends.
The most common check engine repair was “replace catalytic converter.” With consumers holding onto their cars longer than ever before and tariffs looming, CarMD urges drivers to stay on top of regularly scheduled maintenance to reduce the likelihood of needing expensive parts and repairs.
“With uncertainty about how tariffs will impact replacement part prices, it’s particularly important for drivers to address their car’s dashboard warning lights,” said David Rich, CarMD technical vice president. “Catching problems early can reduce the likelihood of a snowball effect from additional repairs.”
The following is a breakdown of the 10 most common check engine light-related repairs in 2024 and the average cost (including parts and labor) to make that repair:
1. Replace catalytic converter(s), $1,348
2. Replace oxygen sensor(s), $254
3. Replace ignition coil(s) and spark plug(s), $400
4. Replace mass air flow sensor, $323
5. Replace EVAP canister purge control valve, $144
6. Replace ignition coil(s), $218
7. Tighten or replace fuel cap, free to tighten; $28 on average to replace
8. Replace fuel injector(s), $464
9. Replace thermostat, $254
10. Reprogram powertrain control module, $108
Other findings from year’s CarMD Vehicle Health Index Check Engine Report:
• Aging vehicles contribute to more expensive repairs. The most common check engine-related car repair in 2024 was “replace catalytic converter(s),” which is back atop the list after a year hiatus. Catalytic converters usually don’t fail on newer vehicles unless a related root cause — like a faulty spark plug or O2 sensor — is ignored. As consumers keep their cars longer, vehicles will outlast parts like catalytic converters. It’s not surprising to see this repair more frequently as drivers hold onto their vehicles longer than ever before with the average vehicle age at an all-time high of 12.6 years.
• Parts costs down. Labor costs up. In 2024 check engine light-related car repair costs dropped nearly 3% to $415.31 from their all-time high of $427.56 the previous year. Labor rose slightly, up 1.4%. But parts costs were down 5% in 2024, likely a flattening after an 8% rise in parts costs the previous year. It’s important to note that while an increase in labor costs could be partially due to wage increases across the U.S., it’s most likely that labor costs are up because of more difficult, time consuming repairs.
The 2025 CarMD Vehicle Health Index analyzes more than 31 million failures and recommended repairs for dashboard warning lights on vehicles in the U.S., over the past calendar year. The data comes directly from each vehicle’s OBD2 system, reported by millions of vehicle owners and the professionals who service them. The failure and fix data are validated by CarMD’s network of Automotive Service Excellence (ASE)-certified technicians.
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