1998 Civic DX D16Y7 just got it off a friend with a no start issue. Replaced the head gasket and I tried removing this sensor but I yanked on the head by accident and it ripped the sensor in 1/2. What is this sensor for? Does it have anything to do with coolant? Coolant temp gauge in the dash does not move past cold so I'm just assuming.. any help is appreciated thanks

It is located directly under the distributor next to the heater hose.. http://i40.tinypic.com/242sirq.jpg

 

Yes that is the coolant temp sensor for the engine temp gauge.

 

Also often called the 1-wire coolant temperature sender/sending unit.