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New owner - Temp Gauge issue?


August 1, 2017
Reaction score
City, State
Colton, SD
Year, Model & Trim Level
2016 Platinum
Hello all. Brand new 2004 Sport Trac owner. 119000 miles. Great shape overall. I just bought this truck over the weekend for my son and runs and drives great. Trailer the vehicle home from a good distance away and took it for a drive on Monday evening with no issues. Today he started the truck with his remote start about 10 minutes before he left, then on his way to school he called me when only about a mile down the road. He said the temp gauge showed it past hot. I had him come back home and look at the gauge myself. It was at least a half inch Beyond the hot side of the indicator. I open the hood and felt the radiator cap and the engine did not seem to be radiating excessive heat at all. I believe it's a gauge issue but would like to confirm this. Since I'm new to the 4 L I would appreciate any suggestions but it's my experience when a gauge seems Peg like that there's usually a sensor problem because I think it would take a lot for it to go completely off the scale hot like that. Especially after just 10 minutes of idling and 35 degree weather. Thoughts welcome. Thanks.

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A pocket of air in the cooling system can make the gauge act out of the norm. also. I am not saying that is your problem, just something to think about. With the truck cool, make sure cooling system is full by removing pressure cap and start engine and watch it come up to temperature just idling, that way if it starts to get too hot you can just shut it off. Turn heater on to make sure water is flowing through heater core. Watch your temp gauge and the engine at the same time, if the gauge moves erratically before the thermostat opens, could be a pocket of air, or the sending unit itself. You can observe engine temperature by just feeling the top, and lower radiator hoses, top hose should be hot, the bottom hose should be cold until the thermostat opens, then the lower hose will start to feel warm, but should never get HOT because that is the cool water going back to the engine. You will also feel the engine fan pulling the air though the radiator, and when the thermostat opens the air behind the fan will become very warm (don't put hand into fan though). Now you can observe your gauge in the instrument panel for wonkyneess!

Did the check engine light turn on?
If it did not throw a Temperature higher than expected code, I would assume there is something wrong with the sender, wiring or possibly the gauge.

Believe it or not, it could be a wiring connection issue. This thread may help. Merely re seating the connectors might solve the problem, and, it won't cost anything but a little time to try.

2nd gen issues? Try this first!

Thanks for your replies. A lot of great info. To answer the last question, there were no check engine lights or anything of the sort that came on. Everything seemed completely normal other than the gauge sitting way above max. I will investigate more this evening.

See attached image. It moves a little with each key cycle. Nothing else out of the ordinary and no warning lights. Heater works fine. Upper rad hose hot, lower cool. No leaks. Now thinking actual gauge problem. Maybe I should just splice an aftermarket gauge in?


Used my Bluetooth ODBLinkMX to check things out and engine temp is fine. Definitely the gauge in the cluster. Wonder how one fixes that?


Used my Bluetooth ODBLinkMX to check things out and engine temp is fine. Definitely the gauge in the cluster. Wonder how one fixes that?

View attachment 163650

Once again, other members have reported fixing the issue by following the link I provided in my earlier post.

Aah yes. Should have mentioned but I did try. Removed both connectors, inspected, and blew them out with my air compressor before reseating thrm and bolting them down. Didn't work for me but I gave it a shot!

You might want to check the temperature sending unit for the gauge. Your truck has 2 temp sensors. One for the PCM which you monitored above, and, another which is just a gauge sender. I think if the sender is shorted it will spike the gauge.

There could also be a problem with the gauge itself. The cluster is serviceable, you can replace just the temp gauge.

I have the same issue with my Gen2 Explorer. I've tried replacing sensors, checked wiring, the gauge itself and verified via OBDII bluetooth to ensure PCM is getting a correct reading...a mirror of the same problems. I put the issue on hold to deal with in the future, please keep posting results. :) If all else fails, I am contemplating on putting a separate gauge on the A-pillar...

With the needle in that position the problem must be that the gauge is bad. I'd add an aftermarket water temp gauge, but it may be difficult to find a place to screw in the sender that comes with the gauge. Especially if you have the push-in style OE temp sender and it's very unlikely that the OE sender will work with new gauge.

I ordered a little gauge off Amazon that you can plug into the obd2 port and set on the dash so he can monitor engine temp until I decide what I want to do long term. I will look into that secondary sending unit that drives the gauge. Can anyone share where it is located? Simply unplugging it should tell me all I need to know.

On the 2001-2002 the sensor for the PCM and the sender for the gauge were located on the top of the plastic t-stat housing. At some point one of the two was removed from this location, but IDK about the 2004. On the image below you can see the location for one and where the other one used to go.

Yep, on this one, there is only one sensor in the housing. There is a port for a second one but it's blocked off, so the sender is presumably elsewhere.

Not necessarily. IDK if the one that you're seeing is the temp sender or the coolant sensor. Check an wiring diagram for your year so you know what you're looking at (unless someone else can say).

Whichever one it is, it's the push-in type, is sealed with an O-ring and is retained with a clip.

@swshawaii - Your ST is a 2004 isn't it?