What are signs I need to change my engine’s spark plugs?

Your car may display one or more signs that indicate you need to replace spark plugs in your engine.

1. Trouble starting. This could happen due to a damaged or worn spark plug wire or spark plug misfiring.
2. Worse fuel mileage. Have you been filling up your gas tank more often? Poor fuel mileage could be due to a misfiring spark plug or two. Misfiring spark plugs may reduce your car’s fuel efficiency by as much as 30 percent.
3. Rough idling. Your car’s engine normally idles quietly and without any shaking. You might hear your engine making rattling, knocking, or pinging noises due to wayward vibrations.  
4. Check engine light comes on. Have your chosen technician diagnose the problem.
5. Slow acceleration. If your car doesn’t respond as it normally does when you accelerate, a problem in the combustion chamber may be the culprit.