Old Cars Costing More to Repair While Car Part Prices Down

With American drivers holding onto their vehicles longer than ever before, the cost of keeping those aging cars on the road is beginning to show. According to the newly released 2025 CarMD Vehicle Health Index, the most common check engine light-related repair in 2024 was the replacement of catalytic converters—a high-cost fix typically associated with older or poorly maintained vehicles.

Despite this, the report also delivers a bit of good news: the average cost of check engine light repairs in the U.S. declined by nearly 3% last year, dropping to $415.31 from 2023’s record high of $427.56. The annual study, based on more than 31 million real-world vehicle diagnostics, suggests that while certain high-ticket repairs are becoming more frequent, overall repair costs were tempered by a notable 5% decrease in parts prices. Labor costs, however, crept up by 1.4%, driven by wage increases and the growing complexity of modern car repairs.

The Vehicle Health Index, published annually by CarMD since 2011, analyzes data from a wide swath of vehicle owners and repair professionals across the country. It offers a granular view of check engine light-related trends, identifying the top causes of dashboard warnings and the financial burden they carry.

“The check engine light is designed to illuminate when a vehicle’s on-board diagnostics system detects a problem impacting emissions or drivetrain performance,” said David Rich, CarMD’s vice president of technical operations. “Ignoring it can lead to cascading issues that become far more expensive to fix. With potential tariffs on the horizon threatening to raise the cost of replacement parts, addressing problems early is more important than ever.”

At the top of the repair list, catalytic converter replacements averaged $1,348—a steep cost that often stems from unresolved root issues like faulty spark plugs or oxygen sensors. These converters rarely fail on their own in newer vehicles, but as the average car age in the U.S. reaches a historic 12.6 years, such repairs are becoming more frequent.

Other commonly reported fixes included oxygen sensor replacements ($254), ignition coil and spark plug replacements ($400), and mass air flow sensor replacements ($323). One of the simplest and cheapest solutions—tightening or replacing a fuel cap—also made the top 10 list. While tightening is free, replacements averaged only $28, underscoring how some check engine light triggers can be resolved with minimal cost if addressed promptly.

CarMD emphasized the importance of regular preventative maintenance as a means of avoiding these high-cost issues. The company encourages drivers to make use of free diagnostic tools offered at many auto parts retailers and is currently investing in new technologies aimed at helping consumers monitor and understand their vehicle’s health more effectively.

“Catching problems early and understanding what your car is trying to tell you when that light comes on is the best defense against major repairs,” Rich added. “There are more resources than ever available to help consumers be proactive, and we’re committed to making sure they can access those tools.”

The 2025 CarMD Vehicle Health Index also notes the growing challenge posed by increasingly complex repairs, which are often more time-consuming and require specialized knowledge. This, in turn, contributes to rising labor costs—another factor drivers may need to consider as they continue to push their vehicles past previous lifespan expectations.

For consumers, the takeaway is clear: staying on top of maintenance schedules and responding quickly to dashboard warnings not only protects the vehicle—it protects the wallet. As the industry braces for possible parts cost increases, being proactive is more than just good practice; it may be an economic necessity.

The full 2025 CarMD Vehicle Health Index is available online at CarMD.com.