ok i am reaching here...... I did a search before i asked this question but not knowing what to call this sensor i really dont knwo what to search for..... on my 89 s13 there is a couple of sensor connectors mounted to the back of the cylinder head.... one of them is brown with a brown connector.... the connector and sensor have quite a bit of corrosion. I was wondering if anyone knew what this sensor was. I am gonna clean up the connection when i re-install my motor, but i would like to know what it is also....

 

hard to say, i dont know... but you could help yourself out and post a few pictures

 

i would probably say its the EGR and canister control solenoid valve.
but without pics its hard to say

 

sorry i cant do pics i dont have a digi cam. the egr is a good guess though, it does hve 2 vaccum hoses on it. I didnt think i would need pics as there are two connectors right on the back of the head one brown one gray..... oh well i am gonna clean it up either way.

 

one controls the egr valve and the other controls the secondary butterflys inside of the manifold... clean both of the connections and reinstall them according to color...