Any Idea What It Is

[fatgeezer]

I just changed the air filter on my '99 1,8 petrol. I noticed that there was a stray green wire that looks as if it's supposed to go on the white plastic thing that is located behind the distributor cap. I've obviously tried to re-install it but the tiny metal connector on the end of the wire doesn't stay fixed to the white thing.

Engine runs whether the wire is connected or not with no warning lights on the dash. What is the white plastic thing please,and will it do any harm to run it without the wire on?. The green wire just disappears into the loom.

[Dan62]

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