Just while driving up a hill I had my temperature gauge spike all the way to highest point and my check engine light came on. I immediately pulled over and shut off the engine to check out the coolant. Everything looked normal with 0 coolant loss. I started the van with no problems and the check engine light was still on with temp for the max. Factored in it was a faulty gauge and drove. After about 1 hour the temp gauge went down and then fluctuated from normal to max then back and forth for the next two hours. Finally went to normal right before I got home. Searching, I'm guessing it's a bad sensor. Anyone know if there is 1 or 2 sensors? I've read some models have 2. The van ran perfectly fine so not sure if there is a different sensor to the computer. I did change the water pump 2 weeks before this trip but no leaks or other signs of coolant loss.

 

Assuming the thermostat was changed along with the water pump? It wouldn't take but a small nudge on an old temp sensor to break it. I'm pretty sure you have only one temp sensor located just left of the thermostat housing looking into the bay.
Mine broke just disconnecting the plug to make room to drill out a snapped bolt while changing out my thermostat and housing a while back. Easy enough to get at to check/replace if the alternator is out of the way.

 

thanks. I can see it behind the alternator. Looks like I can remove it pretty easy without even removing the alternator. I tested the voltage at the wiring harness and got the 5 volts. Ordered a sensor. I changed the thermostat about 2 weeks before the water pump. I decided to change the water pump as preventative maintenance but found nothing wrong with the old one. I was having overheating problems since last year so I changed the radiator/thermostat, removed the clutch fan and replaced with an electric fan first. Van ran cooler but still a little warm on big grades so I did the water pump last to see any changes.

 

Which code did you get? The single-wire sensors should not have teflon tape installed on them as it will interfere with the circuit.
Steve

 

It was P0118. The sensor I found seems to have 2 wires.

 

Two wire sensor is the one you want. You either have a short in there, or a bad sensor.