Hi i just picked up a 2000 civic si and the coolant gauge does not work. I was wondering if anyone could give me an idea on how to go on diagnosing this and what to check first and how

 

Is your check engine light on? if so, scan the system and it should pin point you the problem.

 

The gauge on the dash has nothing to do with the computer. Assuming the engine warms up properly (the heater puts out plenty of heat), check the gauge system. The gauge sender is below the distributor (on SOHC, I think also on DOHC heads). It has one wire, make sure the wire is plugged in securely or it will stay at cold. It's very common for the wire to get left off after R&R transmission to replace clutch, etc. If you ground the wire and turn the key on, the gauge should go up toward hot (don't leave the key on and let it slam all the way at hot).

 

Alright Ill try that I get off work early tomorrow so ill see what it does when I ground it to the block and let you know if it shoots up. If it does shoot up does that mean i need to go pick up a new sensor?

 

Pulled the wire off and grounded it so the sensor must be the cause