Do Spark Plugs and Ignition Coils Need to Be Replaced Together?
2 Answers
Spark plugs and ignition coils do not need to be replaced together. The function of the spark plug is to ignite the mixture in each cylinder, while the ignition coil converts low voltage into high voltage to provide the spark plug with high-voltage electricity. Steps to replace spark plugs: Open the hood, lift the plastic cover of the engine, and remove the high-voltage wires. Make sure to mark the position of each cylinder to avoid confusion. Use a spark plug socket to remove the spark plugs one by one. While removing them, check for any leaves, dust, or debris on the exterior and clean them thoroughly. Place the new spark plugs into the spark plug holes, hand-tighten them a few turns, and then use the socket to tighten them further. Reinstall the removed high-voltage wires according to the firing order, and then secure the cover. Spark plug replacement interval: Under normal maintenance conditions, spark plugs should be replaced every 40,000 to 60,000 kilometers. However, this may vary depending on the brand and engine type. It is recommended to follow the instructions in the owner's manual.
I remember last summer, my old SUV always felt underpowered and had slight idling vibrations. After a check-up at the repair shop, the mechanic said the spark plugs were severely carbon-fouled and recommended a full set replacement. When I asked about the ignition coils, he mentioned that if they've been in use for several years or show signs of issues—like electrical leakage or heat discoloration—it's best to replace them together. This prevents overall ignition system failures, especially common in high-mileage vehicles. Doing it all at once saves labor costs and avoids repeated hassles. Of course, not all cars need this; my compact car only required spark plug replacement. The key is assessing the vehicle's condition and driving habits—highway driving causes more wear, while city commuting isn't as urgent. I typically inspect every few thousand kilometers and log it in the car manual. Don't blindly follow advice about replacing everything—get an accurate diagnosis first.
