Changing your spark plugs is one of the easiest jobs you can do on your car, yet many people don’t did it themselves. If you’re suffering with poor gas mileage or have had a warning light come up (usually P0170 - Fuel Trim Malfunction) then changing the plugs may help fix this. We’re going to walk-through the easiest way to change these so you can save time and money by doing it for yourself.
What you need:
- A ratchet with an extension attachment
- 5/8 socket head
- Replacement spark plugs
Remove the HT leads from their housing on the spark plugs. You should only need a small amount of force to pull these out. Don’t pull them by the leads, instead grab them as close to the casing as you can and lift them out.
Pro Tip: Change your spark plugs one at a time. This will stop you from getting confused as to which lead goes to which spark plug. If you get these wrong then you can end up misfiring. If you do want to get them all out at the same time, put a sticker on the HT leads so you know where each of them sits.
Use the 5/8 socket head to remove the old spark plugs from within the engine. Try not to be too forceful with them as this can cause them to break or damage the threads on them.
Pro Tip: Before you remove the plugs, grab a flashlight, check for dirt and debris around the base of the plug, and clean up whatever you find. You don't want any of this "gunk" falling into engine when you're removing the plug. A bit of compressed air is all it takes to "blow out" any of the gunk and get it clear.
Once out, measure the distance between the points of the spark plug. This will give you a good idea how badly worn they have become. The ideal distance between the points will be listed in the manual for your car, if not, a quick search online will tell you what you need to know. If the gap is fine, then there may not be a need to change them, but it’s always best to do so. You can get a spark plug gap tool online for very cheap and I recommend everyone owns one.
Before putting the new spark plugs into place, add some anti-seize or copper grease to the threads of them. This will make it much easier to get them out next time you need to change them. Be sparing with it and wipe away any excess that’s on the plugs.
Put the new plugs into their housings and tighten them. Do not over tighten them. This again can cause them to break or make them impossible to remove in the future.
Reattach the HT leads in the right order. These should simply just press into place with minimal force. Make sure all of them are making contact to prevent any misfires.
Start the car to see if it fires correctly.
I mentioned earlier about the P0170 fault code. If this does come up try using some injector cleaner first. I had a few issues with this code myself and found that this worked well in the short term. Failing that, or if changing the spark plugs doesn't work then change the O2 (lambda) sensor. This should fix the problem for good.