Has anyone had an issue with their temperature gauge shooting all the way up when you are driving down the road which causes the "Check Engine Temp" light to come on and then the temp immediately drops down to the normal midway range? This generally happens once, maybe twice a day, but then sometimes skips days. Wierd! I have had the dealer check it and it isn't pulling any codes as having something wrong. I had some electrical issues with the dash panel a couple of times and it was replaced a a couple of years ago (it caused the power windows, doors and radio to not work). I can't figure out whether it is something else relating to that or something entirely different. Any guidance from someone that has had the same issue would be great!

Thermostat?

No, they checked that and said it was fine. It does not seem to cause any issues, but it's still very strange

Mounty03,


What type of issues did you previously have with your guage cluster? I'm having an issue with the drive selecter not returning to park, the trip counter will switch to actull car miles with out me pressing it, and (not sure if its the cluster) the tank level doesnt always return to full even after just filling up.

No issues like you describe. Mine were all electrical. The car would almost go into "lock down". None of the door locks or power features would work (windows wouldn't go up or down). Luckily the air conditioner wasworking because when it happened the 2nd time it was middle of summer and about 100 degrees outside. It was really odd. Your issues seem more mechanical than electrical, but it's so hard to tell. I have decided to just live with the temperature gauge quirks b/c it didn't pull any codes when they did the diagnostic. What year is yours?

Mine is doing the exact same thing - it shoots up to H, then comes back down after a minute. I assume this has to be a sending unit issue for my 03 Mountaineer as well.

I've looked around Autozone.com, but can't find the part - maybe I'm searching for the wrong keywords or it's called something else. Any ideas anyone? If I can find the part, does anyone know where the sending unit plugs and screws into?

I had this exact same thing happen with my oil gauge a year or two back and it ended up being the sending unit for that as well.

One other question - the dealership and Autozone both had trouble finding a sending unit for the 03 Mountaineer - does the ECTS double as the sending unit for the gauge?

Looks like there is no sending unit for the '03 Mountaineer. I replaced the ECTS while the car was hot like an idiot and got a face/hands full of hot coolant - luckily, I was able flush my eyes quickly and no pain there, but my hands are a tad burnt...

Anyway, that did no good and it looks like a bad thermostat after all, which is weird since I was getting false H readings on the temp gauge. Just thought I'd finish this post up in case anyone needs to look it up in the future.

Make sure there is no air in the coolant system, have seen many air pockets that can cause a high temp reading. Can happen from a leak or stuck/ failed tstat. Do a pressure test, check your fluid for contamination, if it dirty you could have a blockage in the rad or heater core. As for the elec issues sound like a faulty ground or a short to ground.

I would hope Mounty got his problem resolved since he posted this over 13 years ago!