Spark plug
Also asked for as: plug, spark plug, iridium plug
What it does
Ignites the air-fuel mixture in each cylinder.
Signs it needs replacing
- Engine misses or jerks
- Hard starting in the morning
- Fuel average drops
What to tell the shop
- Vehicle make, model and model year
- Engine size, and whether it is manual or automatic
- The number printed on the old part, or a photo of it
- Whether you want genuine, OEM or a local replacement