Replace spark plugs and spark plug wires
Average repair cost: $361.56
Replacing spark plugs and wires accounted for 3.28% of repairs. Replacing a spark plug can cost just $10 if you do it yourself, but drivers spend $361.56 on average to have spark plugs and their wires replaced by a technician. When these items fail, they can cause the engine to misfire and gas mileage to decline. Ignoring the problem can result in permanent damage to your car's expensive catalytic converter.