For the price of sparkplugs it is always worthwhile changing them as part of an intermediate service to keep the engine performing well. In order to do this, you will need an HT lead removal tool. Do not attempt to remove the HT leads with anything else as they are very fragile and will break. You can source the correct tool for anything between £5-£25. This is not a genuine smart one, but perfectly adequate:
To start the job, you need to remove the rear panel from the car. Then remove the crash bar.
Start with the lower plugs. Push the removal tool in around the HT lead over the top of the sparkplug head. Rotate until it engages with the lead.
Now pull. Be careful when you do this. It takes quite a lot of force to remove them and when they do come free, be careful not to jar the leads. Repeat for all three leads.
Remove all three spark plugs with a sparkplug socket set. You will notice that these lower plugs will be quite dirty. This is perfectly normal.
Replace with new plugs and tighten as per the instructions on the side of the sparkplug box.
DO NOT overtighten sparkplugs as you risk stripping the threads. Remember, the fortwo engine block is only made out of aluminium.
Refit the HT leads with the removal tool in the reverse way to removal. Push hard until you hear them click back into place.
Remove the top three HT leads in the same way as for the bottom. Take great care not to snag the leads on the edge of the engine bay when you they come free.
Loosen all three sparkplugs. You may need to use some long nosed pliers in order to lift them out.
Fit the new plugs and tighten as per the instructions on the side of the sparkplug box.
Refit the HT leads and ensure they are fully engaged.
Start the car and check that all cylinders sound like they are firing correctly. Refit the rear panel and crash bar.
As a note of warning, some less reputable service centres may avoid changing the lower 3 sparkplugs as removing the rear panel is deemed as being too much work. We found the following example when we serviced the particular car ourselves. The car was reporting a misfire - looking at the shape of the electrode on the old plugs, we weren't surprised!
