Oil on the air con temp sensors? puegot 206?

Question

My partners puegot 206 has been "running away" on start up, if she is driving at the time the car stalls.
I have just checked the eng man coolant temp sens (green plug), needed a little clean (limescale) but okay, then checked the air con cont sys temp sens (brown plug), it was covered in gunk / mayonaise / oil.
Never checked the coolant temp gauge (Blue plug), couldnt reach it.
2 Questions for you all.
1, Does the oil on sensor mean a head gasket change, as it wasnt on the other sensor?
2, Would this contribute to the engine "running away", Or would you reccommend any other investigation?

I am an aircraft engineer, so have a good engineering background (i think?)

Thankyou in advance for your time and trouble, much appreciated.

John

Answer 1

A temperature sensor should not affect the engine speed at all.

You may want to look around the engine intake manifold for a small hose that came off causeing a vacuum leak.