Just fitted downpipe and these a threaded hole just before the last bend.

It open at the mo, but what should go in there???

If anyone knows the thread size please help so i can block it off.

IF unable to block off as no-one knows the size can i drive my car??

Thanks for your help

David

 

Probably for the temerature probe fitted to jap imports. Not on UK cars. Just block it up

 

David, I think it's a 12mm *fine* thread for that hole.
The same thread as your wheel nuts.

A