As with other components in your Camry, the sparkplugs have their own life cycle. Hydrocarbon deposits on their electrodes or a crack in their insulating ceramic layer will surely end their life.
Replacing them is pretty easy and you will need some basic tools, like a 10mm ratchet and a sparkplug wrench. It is also recommended to replace all of them and not one or two. So here are the steps:
- Open up the hood
- Unscrew the two nuts on the engine cover
- Take out the engine cover
- Unplug the wires for each sparklug coil
- Unscrew the bolts holding each coil
- Take the coils out
- Unscrew the sparkplugs and take them out
- Replace them with new ones
- Tighten the sparkplugs carefully not to damage their threads
- Put everything back.