No. 8: Bad spark plugs and spark plug wires
Average repair cost: $331.13
Dropping one spot from last year, this represents 3.42% of repairs.
Replacing a spark plug can cost just $10 if you do it yourself, but drivers spend $331 to have spark plugs and their wires replaced by a technician. When these items fail, they can cause the engine to misfire and your gas mileage to decline. Ignoring the problem can result in permanent damage to your car's expensive catalytic converter.