So car was misfiring 2 weeks back and giving a p0304 code. Changed the spark plugs and it worked fine until this week when it started again but worse, giving a p0302 code. Naturally tried changing the coil packs but made zero difference.
When I was changing them I noticed this plug (see below) has almost completely melted through. Could someone tell me please what this is/does please and if it could cause my symptoms? Thanks
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