Used Spark Plug 1972–2019

A spark plug screws into the cylinder head and fires the electrical spark that ignites the air-fuel mixture in each cylinder. As the electrode gap widens and the insulator degrades over miles, ignition reliability drops and you start feeling it. Symptoms of worn plugs include a rough idle, engine misfires, poor fuel economy, sluggish acceleration, hard starting, and a check engine light with misfire codes. Fouled plugs from oil burning or a rich mixture have their own smell and color patterns that help narrow down the root cause. Redline lists spark plugs for 29 makes with 158 ignition-related parts from 7 sellers. Used plugs pulled from low-mileage engines, especially premium iridium or platinum types, can offer real value for budget repairs where new plugs would cost far more. Search by year, make, and model to find plugs for your engine. Gas engines from Ford, Honda, Toyota, Chevrolet, Chrysler are well represented. Always match the heat range and thread size to your engine's spec since the wrong plug can cause pre-ignition or poor combustion.