Im pretty sure its 12x1.5mm

Cheers dude.

great idea. now all I need is a tap to tap it out!!

Dont suppose anyone has one I can use??

Most A series engines either have an undrilled pad, or a threaded hole in the head in front of No. 1 exhaust port. It's there to mount a temperature sensor for a smog related device & it senses the same temperature that the thermostat & the temperature guage unit sees.

This is an ideal place to locate a temp sensor for the Haltech & using this location allows the original temperature guage to remain operational, so it's a win win situation.

If your head is undrilled, then BONUS as you can drill & thread it for the fitting that you already have.
If it is already drilled, then simply grab the original temperature switch as a size sample.

You can see what I mean in this picture. The switch position is on the manifold side right near the front of the head.

hey guys,

I need to know the thread size for the A15 temp sensor. I have a haltech computer sensor to go in there and it is imperial 1/4 npt

Cheers -Liam