TL;DR is 2004 Ford Focus zts 1.3L temperature gauge does not move and stays on full cold. Radiator fans operate on high the entire time. RPM fluctuates and is sporadic around the 500-2000 range.

Additional information below:

The car used to overheat while idling which is where the maintenance began. I realized this was due to the fans not being on at all. The low speed would never turn on until the car started to overheat and then the fans would kick on full blast on high until the car cooled down or I started moving again cooling the radiator off with ambient air while driving. The temperature gauge read perfectly while this was happening. I decided to replace the coolant head temp sensor to see if this would fix the initial issue and after replacing the sensor the temperature gauge began having problems.

When turning the car on the needle will do different things, sometimes the needle pops up to the halfway mark, sometimes a quarter, sometimes it just twitches at full cold, then when you turn the car over the needle will pop right back down to full cold and stay there regardless of how long the car is on or how much you rev engine.

Any help troubleshooting this would be greatly appreciated as this is my wife's car and I only have about 2 weeks until I deploy. Sidenote: I've tried a second coolant head temp sensor in case the first one was bad out the packaging but had the same results.

 

:SOLVED:

So one of the temperature sensors was bad out of the box (I ordered the one that looks just like the oem one from amazon), I got an aftermarket one from Oreily's because the part is discontinued by ford. The connector is different so I had to cut the wires on the old one and splice the new connecter (that comes with the part from oreily's) in. I was confused because the gauge doesn't read instantly after installation. You have to disconnect the negative on the battery and leave it disconnected for a couple minutes, wire in your new sensor, connect the sensor then reconnect battery. This will clear your check engine light if you have one and it allows (I assume) the PCM to relearn this new sensor. I had to wait about 10 minutes before the gauge started to read with the new sensor installed. So be patient and let the computer do it's thing. Gauge reads perfectly . now and all is resolved, I'm just leaving this info here in case anyone has this problem in the future.

Another bit of information that might help you is this : For troubleshooting whether it's the sensor or the wiring that's faulty, with the key in the ignition and turned to on (engine off) you should have about 3V on one wire
of the connector to the cylinder head temp sensor, the other wire should have a good path to ground. If you have power and ground, you know your sensor is bad, if you're missing power or ground then look into your wiring as you may have an open.

Additionally a lot of people with this issue have had problems finding a tool that can remove the sensor without breaking the connector off. Attached is a link to amazon where you can find a tool that will clear this connector and remove it successfully. If you like to use snap-on the snap-on number for a tool that will also work is S6203.


Link for cylinder head temp sensor: https://www.oreillyauto.com/detail/c...p+sensor&pos=6

TS464 is the part number in case that link ever fails to work.

 

Thank you for the info.