Is Your Check-Engine Light stable on? here 5 of the Most Common Causes
Is Your Check-Engine Light stable on? here 5 of the Most Common Causes

Is Your Check-Engine Light stable on? here 5 of the Most Common Causes



April is Car Care Awareness Month — and also National Canine Fitness Month, International Guitar Month and National Soft Pretzel Month, among many others — and the folks at CarMD are back with their 2021 Vehicle Health Index, which documents what causes your car’s dreaded check-engine light to illuminate.
Related: Which Cars Have Free Maintenance for 2021?


While last year’s report had the top 10 causes, this year’s report limits the list to five. It’s not clear if that’s another example of pandemic-related cutbacks, but CarMD does find it likely that the pandemic has impacted car repairs. Repair costs have decreased year over year by an average of 1.6%, with labor costs decreasing by 2.8% and parts costs decreasing by approximately 1%.


“Many factors likely played a role in this decrease, including the economy, competition among repair shops and an increase in DIY [do it yourself] automotive repairs during the pandemic,” CarMD said in a statement. The lowered costs for 2021 don’t paint a rosy picture for next year’s report, however, with potential supply-chain disruptions possibly resulting in increases in future parts costs.


One bright spot in the report relates to newer vehicles. According to CarMD’s data, cars less than 3 years old made up fewer than 1% of all check-engine-light-related repair issues. By comparison, model-year 2007 vehicles alone accounted for 9.9%.
The five most common issues, according to CarMD, along with their respective average costs to repair, are:
1. Replace catalytic converter(s) with new original equipment catalytic converter(s), $1,383 | #565,011.96


2. Replace oxygen sensor(s), $243 | #99,275.42

3. Replace ignition coil(s) and spark plug(s), $389 | #158,922.38


4. Replace mass air flow sensor, $336 | #137,269.72


5. Tighten or replace fuel cap, $25 | #10,213.52


Catalytic Converters Are Hot
One explanation for the frequency of catalytic converter replacements is a lack of regular maintenance.
“We don’t want people to panic when they hear that catalytic converters are the most common repair,” David Rich, CarMD technical director, said in a statement. “It’s important to remember that while catalytic converters are costly, they 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.” Vehicle age may also play a factor, as the average increased to 11.9 years in 2020.
Another possible explanation is the increase in catalytic converter thefts. While 2019 saw an average of 282 catalytic converter thefts per month, according to National Insurance Crime Bureau statistics, 2020 saw an average of 1,203 thefts per month.


Easy Fix
As for the fifth most common repair — tighten or replace the fuel cap — be sure to check your fuel cap if your check-engine light comes on. It may be loose or not closed at all following a recent fill-up, and properly tightening the fuel cap yourself is likely one of the easiest DIY car repairs.

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