Not listed in my manual, on the right center of the firewall is a sensor type thing with 3 wires and what looks like a vac hose connection with a white collar around it. Does anyone know what it is and should it be fed a vac signal? Thanx and merry Christmas.

 

What vehicle, year, engine, drive train, etc.? You really didn't give much information to go on.

 

Sorry, it's a91 4x4 and whatever it is it caused a no-start, I cleaned the connexions and she's running fine. However when disconnected I get a check engine light and it still runs. I'm baffled.

 

Barometric pressure sensor? I know some years had them. What code does it leave in memory when it's disconnected?

 

That's right it is the BAP will pull codes soon, looking after the wee ones right now.