Faulty oxygen sensors are still the most common cause of a check engine light, says the the 2017 CarMD Vehicle Health Index released Tuesday. 

According to CarMD’s findings, model-year 2005 vehicles were most likely to have a check engine light on and newer-model 2015 and 2016 vehicles make up less than 1 percent of reported check engine incidents.

"While check engine issues can occur on any age vehicle at any time for many different reasons, this report reminds owners of 10- to 12-year-old vehicles to be vigilant with their maintenance routines and to be prepared for the possibility of a check engine light repair," CarMD technical director David Rich said in a news release. "CarMD has monitored car repair and maintenance trends for two decades and found that when vehicles are properly maintained, they tend to experience fewer check engine light problems than those whose owners put off scheduled maintenance and small repairs."

CarMD examined data from 5.3 million-plus 1996-2016 vehicles inside the U.S. and on the roads during 2016.

Analysts took a look at 5,345,588 repairs reported to and validated by CarMD's network from January 2016 up to the end of December.

Last year, the average cost to repair a check engine problem was $398, which is up 2.7 percent year-over-year, according to the index.

Five top common problems found to trigger the check engine light in 2016, according to the index, were a faulty oxygen sensor, catalytic converter, ignition coil and spark plug issue, loose or damaged fuel cap and faulty mass air flow sensor. 

The following lists the five c check engine light-related car repairs along with their average repair costs, according to CarMD.

1.    Replace oxygen sensor – $258

2.    Replace catalytic converter – $1,190

3.    Replace ignition coil(s) and spark plug(s) – $401

4.    Tighten or replace fuel cap – $17

5.    Replace mass air flow sensor – $378

“Car repairs and associated costs can be affected by region, maintenance decisions of previous owners, as well as the vehicle's age,” CarMD said.

In the West, vehicle owners had a 1.1-percent drop in car repair costs, drivers in the Northeast paid the most for check engine repairs and drivers in the Midwest paid the least for parts and labor, according to the the automotive diagnostic information provider.

The report also found that vehicle age affects the likelihood of engine light-related car repair as well as the type of repair.

CarMD said 11-year-old model year 2005 vehicles accounted for 10.8 percent of check engine issues reported to CarMD in 2016 and were most likely to report having a check engine light on.

The full Index includes: the 25 most common check engine-related repairs; the percent of reported check engine light repairs by vehicle age; an 11-year history of U.S. car repair costs; a  list of the most common repairs by region; and the 10 least and most expensive repairs.

To view the detailed 2017 CarMD Vehicle Health Index report click here.

Additionally, the automotive diagnostic information provider has introduced a new service called CarMD Garage now available online at www.carmd.com/garage, which aims to guide consumers to make informed decisions regarding repair, maintenance, used car and parts purchases.

CarMD Garage was designed to help car owners keep up with car maintenance by providing reports that show any services due on their vehicle, according to CarMD.