My temp gauge isn't working. If I stomp on it or hit a bump, it will shoot over to the other extreme, so if it were at 260 it will shoot over to 100 and vice versa. I just put on some shorty headers and had to remove a sensor on the drivers side down just above the oil filter. About 2-3" long and bright silver. I unplugged it and removed it to get the header in. I then reinstalled in but couldn't get it super tight due to cramped space. I plugged the connector to it back in, but coming of the lead of the connector is another connector, orange and it looks different than the other connector, kinda like a small Ethernet plug you would put in the back of you home phone. I can't remeber of it was plugged in some where when i started or not. If any of these sound like the problem please let me know. Any help is greatly appreciated guys. Maybe I'm just missing that little orange ones plug in or maybe that long silver one is too loose.

 

The temp gauge sensor is in the front drivers side of the block, between the 1 and 3 cylinders. There is plenty of room to get to it, even with shorty headers and I, at least, had no problems getting the headers in around the sensor.

 

You might have disconnected your oil pressure sending unit to get the headers in. I believe that it is also a fuel pump safety, allowing the fuel pump to run only when you have oil pressure.

 

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If the wire to the temp gauge sending unit touches ground (ie: headers, block), the gauge will peg, just as it does during engine crank.
It's dark green in colour.