10th Annual CarMD Report On Check Engine Light Causes

Check Engine Light
Photo Credit: Daniel Krason/Shutterstock
It’s the 10th anniversary of CarMD’s annual check engine light report. It sheds “light” on the main reasons car owners may see their engine light come on and provides repair cost data. Check engine lights monitor emissions and drivetrain issues and ignoring them can often lead to expensive repairs. (Last year, the average cost to repair a check engine light issue was $384 – up 1% from 2018.)

2020 CarMD Vehicle Health Index

The 2020 CarMD Vehicle Health Index includes a year-over-year ranking of the top most common check engine light repairs and associated costs in the US. It’s also a look back on a decade of diagnostic data from more than 41 million unique vehicles to identify how the type and cost of repairs have changed as vehicles become more technologically advanced.

“Recognizing that the check engine light was often misunderstood and feared by vehicle owners, CarMD initially released its Vehicle Health Index to educate consumers about the importance of addressing the check engine light to minimize repair costs and maximize vehicle life,” said Ieon C. Chen, CEO, CarMD.

Consider this: Today’s cars have more computerized sensors than ever before. In 2010 CarMD identified 675 different possible fixes for a check engine light. In 2019 that nearly doubled to 1,283.

The big surprise this year? The “replace catalytic converter” tops the list for the first time ever as the most common check engine light repair. (Last year, “replace oxygen sensor” and “replace ignition coil(s)/spark plugs” tied for number one.) Fixing a catalytic converter isn’t typically cheap, either. Catalytic converters don’t typically fail unless maintenance and other repairs (like a faulty oxygen sensor or ignition coil) are ignored, or a vehicle has high mileage. The latter of which can be partially explained by the increase in average vehicle age from 11.7 years in 2018 to 11.8 years in 2019.

Replacing a catalytic converter was a pricey expenditure ten years ago, and still is today. The average cost in 2019 was $1,375; back in 2010 the same repair averaged $1,008.

A common precursor to catalytic converter failures, “replace oxygen sensor” has ranked as the most common repair for eight of the 10 years this Index has been reported; in 2019 it was the second most frequently recommended repair.

Here are the top five check engine light repairs in the 2020 report:

  1. Catalytic converter
  2. Oxygen Sensor
  3. Ignition Coil and Spark Plug
  4. Gas Cap
  5. Mass Air Flow Sensor

Other Findings:

  • Mass Air Flow Sensors (increased): CarMD researchers note an increased percentage of MAF sensors and fuel injectors needing replacement.
  • Gas Cap Issues (dropped): A repair that has become less common over the last decade is to tighten or replace a gas cap. The gas cap accounted for 9.2% of repairs in 2010; this past year it dropped to 4.5% of repairs. CarMD researchers say Increased consumer education about the role fuel caps play in vehicle emissions and fuel economy, combined with an uptick in capless gas tanks on newer vehicles, have contributed to the drop.

  • Replace Ignition Coils/Spark Plugs (increased): These issues move from # 20 and 1.1% of repairs in 2010 to # 3 accounting for 5.23% of repairs last year. Ignoring a smaller problem like a spark plug can snowball into the need for more than one repair.

Labor and Part Expenses

  • Average overall labor expense per repair was down just over 5%, while parts costs were up about 6%.
  • Car repair costs were up in three of four U.S. regions, with the exception being the Midwest where costs were down 1.6% over the past year.
  • Various factors impact the type and cost of repairs, including vehicle age, driving conditions, upkeep and how often a driver addresses a dashboard warning light.
  • Over the past decade, the lowest average repair cost was $305 in 2018; the highest average repair cost was $397 in 2016.

About the Report

The 2020 CarMD Vehicle Health Index analyzed recommended repairs needed on more than 15.9 million in-use vehicles reported to and validated by CarMD’s network from Jan. 1, 2019 to Dec. 31, 2019.
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