I just bought a 99 V6 3.8l; ~70k on replaced motor. I replaced the TB due to a throttle position code [p1515] and it runs fairly well now. It had an incorrect serpentine belt and a broken engine coolant sensor [code P1118, P1119] and broken sensor connector. I replaced the belt and sensor (located directly under the TB) and spliced the sensor plug. My SES went out for a few minutes, but is back. New code is P0118. Advance Auto suggested a new T-stat. BTW, the temp dash indicator needle is not functioning at all. I think the fans run all the time. Prolly unrelated, but PS is not working.
Any guidance?

 

p0118 is temp sensor circuit, high input. Did you make sure not to get the wires backwards when you spiced it back together? sounds like you need to trace that wire back to the computer, a volt meter or ohm meter would be a wise tool for this. I dont have a whole lot of experience with the 3.8s, but the gauge sensor should be in the cylinder head, the other should be ONLY for the computer, so a false reading there will kick the fans on to protect the engine by default. Please dont just throw more parts at it cause the parts store guys cant figure it out........ Im sure somebody with more knowledge of the 3.8s will chime in with some more suggestions. Try to find a wiring diagram that shows the pinouts on the computer plug so you can test ohms in the wire. I looked in my haynes but am running on no sleep and cant give you a clear answer. Someone here might also know right off the top of their head.

 

I will try with the volt meter, I really hate auto electrical...
The wires are color-coded so I don't think they are crossed, but I need to check the quality of the connection.

Item 4 on the diagram is the sensor I replaced and the outlet for the plug and pigtail I spliced. I need to know where the instrument panel guage gets its info so I can check that connection.