After two years of flat vehicle repair costs for U.S. consumers, 2016 saw a 2.7% increase because of rising labor and auto part costs, according to a new report from CarMD.

Last year, auto repair labor costs rose 4.7% and average auto part costs inched up 1.4%, according to the CarMD Vehicle Health Index. Each year this report highlights the most common “check engine” light-related problems, repairs and associated costs. To compile the report, CarMD relies on its database of failures and fixes tied to vehicles’ on-board diagnostics. CarMD is a major provider of automotive diagnostic information. The annual index is based on data from more than 5.3 million in-use vehicle problems.

In 2016, the most common “check engine” light culprit was the oxygen sensor (which costs, on average, $258 to replace), followed by the catalytic converter ($1,190), ignition coil and spark plugs ($401), loose or damaged gas cap ($17), and mass air flow sensor ($378).

Automotive repair costs went up in three of the four regions in the U.S. The West was the sole region that saw a slight drop in average car repair costs, dipping 1.1%. In contrast, drivers in the Midwest paid on average 5.7% more, compared to 2015, to have their car’s “check engine” light resolved. The average price rose from $364 in 2015 to $385 in 2016.

According to the report, the average age of a vehicle with a check-engine light was 11.9 years old. Not surprisingly, 2015- and 2016-model year cars and trucks fared much better. Each accounted for less than 1% of reported check-engine incidents.

The most expensive repair seen in the CarMD network last year was “replace engine,” which carried an average $7,600 price tag. Some of the least expensive repairs included tightening or replacing the gas cap, replacing the oil cap, and replacing the secondary air injection control solenoid valve vacuum hose — each typically costing less than $30.

To view the report, click here.