Vehicle Health Index

Vehicle Health Index

The CarMD® Vehicle Health Index™ reports on the most common check engine light-related problems, repairs and associated costs. Published annually since 2011, this Index provides year-over-year car repair data.

The check engine light comes on when a vehicle’s computer detects a problem that affects emissions or drivetrain issues. If ignored, it will hurt the environment, the car’s fuel economy and lead to more problems down the road.

Learn More
Vehicle Health Index

The CarMD® Vehicle Health Index™ reports on the most common check engine light-related problems, repairs and associated costs. Published annually since 2011, this Index provides year-over-year car repair data.

The check engine light comes on when a vehicle’s computer detects a problem that affects emissions or drivetrain issues. If ignored, it will hurt the environment, the car’s fuel economy and lead to more problems down the road.

Learn More

2021 Vehicle Health Index

Highlights – Check Engine Light Insight at a Glance

The following is a breakdown of the five most common check engine light-related repairs in 2020 and the average cost to make that repair, including parts and labor. Each of these issues will keep a vehicle from passing its state emissions test and negatively impact fuel economy if ignored.


  1. Replace catalytic converter(s) with new OE catalytic converter(s), $1,383
  2. Replace oxygen sensor(s), $243
  3. Replace ignition coil(s) and spark plug(s), $389
  4. Replace mass air flow sensor, $336
  5. Tighten or replace fuel cap, $25

Don’t panic when the check engine light comes on, but get it diagnosed ASAP. It can be as simple as a loose gas cap. But a flashing check engine light can indicate a more serious problem such as an engine misfire that needs immediate attention from roadside assistance.

  • In 2020 car repair costs were down 1.6% overall at an average of $378.77. Labor costs were down 2.8% year-over-year from 2019 to 2020, and parts costs were down about 1%. Many factors likely played a role in this decrease, including the economy, competition among repair shops and an increase in DIY automotive repairs during the pandemic. CarMD anticipates an increase in parts costs next year given the material shortage resulting from shutdown-related supply chain issues.
  • New this year CarMD broke down the Index by vehicle model year. Model year 2007 vehicles were most likely to need check engine light repairs, accounting for 9.9% of problems seen by CarMD across all models last year. The most commonly diagnosed repair on a 2007 vehicle was “replace ignition coil(s) and spark plug(s).” Not surprisingly, vehicles that are less than 3 years old didn’t experience many check engine light issues, accounting for fewer than 1% of needed repairs reported to CarMD.
  • CarMD’s data reports an increase in mass air flow sensors (MAF sensors) needing replacement, while fuel cap issues continue to trend down. MAF sensors moved from the no. 5 to the no. 4 most common repair. Gas cap issues dropped again moving from the no. 4 to no. 5 most frequent repair. This and other national and regional trend data in the full report can inform automotive parts suppliers, aftermarket retail buyers and other industry experts as they extrapolate year-over-year and trends related to vehicle diagnostic data and related parts failures.
Learn more about CarMD VHI Report

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    2021 Vehicle Health Index

    Highlights – Check Engine Light Insight at a Glance

    The following is a breakdown of the five most common check engine light-related repairs in 2020 and the average cost to make that repair, including parts and labor. Each of these issues will keep a vehicle from passing its state emissions test and negatively impact fuel economy if ignored.


    1. Replace catalytic converter(s) with new OE catalytic converter(s), $1,383
    2. Replace oxygen sensor(s), $243
    3. Replace ignition coil(s) and spark plug(s), $389
    4. Replace mass air flow sensor, $336
    5. Tighten or replace fuel cap, $25

    Don’t panic when the check engine light comes on, but get it diagnosed ASAP. It can be as simple as a loose gas cap. But a flashing check engine light can indicate a more serious problem such as an engine misfire that needs immediate attention from roadside assistance.

    • In 2020 car repair costs were down 1.6% overall at an average of $378.77. Labor costs were down 2.8% year-over-year from 2019 to 2020, and parts costs were down about 1%. Many factors likely played a role in this decrease, including the economy, competition among repair shops and an increase in DIY automotive repairs during the pandemic. CarMD anticipates an increase in parts costs next year given the material shortage resulting from shutdown-related supply chain issues.
    • New this year CarMD broke down the Index by vehicle model year. Model year 2007 vehicles were most likely to need check engine light repairs, accounting for 9.9% of problems seen by CarMD across all models last year. The most commonly diagnosed repair on a 2007 vehicle was “replace ignition coil(s) and spark plug(s).” Not surprisingly, vehicles that are less than 3 years old didn’t experience many check engine light issues, accounting for fewer than 1% of needed repairs reported to CarMD.
    • CarMD’s data reports an increase in mass air flow sensors (MAF sensors) needing replacement, while fuel cap issues continue to trend down. MAF sensors moved from the no. 5 to the no. 4 most common repair. Gas cap issues dropped again moving from the no. 4 to no. 5 most frequent repair. This and other national and regional trend data in the full report can inform automotive parts suppliers, aftermarket retail buyers and other industry experts as they extrapolate year-over-year and trends related to vehicle diagnostic data and related parts failures.

    Vehicle Health Index


    Learn more about CarMD VHI Report

    Please submit your information to have out Vehicle Health Index Data Services Team connect with you shortly.

      Please enter the characters you see in this picture*
      captcha