1997 E-350 5.4L. Starts and run okay. Not boiling over or leaking.Temp gauge needle is up in the red zone once up to temp. Scan gauge indicates ECT 220 - 225. No CEL or codes present. I am trying to figure out if I have an overheating issue or a gauge/sensor issue. I'm assuming that the scan gauge reads the ECT from the same sending unit that the dash gauge uses, so if the sending unit were bad, I wouldn't get a temp reading on the scan gauge, no? 220 seems to be on the high side of normal, but I wouldn't think that would peg the gauge. I'm wondering what temps correlate to the dash gauge. Thoughts?

 

I have a similar problem. My temp will spike to the max and the "check gauges" message will appear. If I pull over - shut down - restart immediately - the gauge goes back to normal. Motor does not appear to be hot. Seems like a bad coolant temp sensor to me. Garage said it would be almost $200 to fix it. Anyone out there know what it takes to replace the sensor? Where is it located? Under the intake manifold?

 

220 isn't an issue. My '97 would hit 230 a few times and that was around 3/4 gauge IIRC. They run from 210-220 in the summer all the time.