Strange Coolant Temp readings on my Livewire

[2003_F350_7.3_Diesel]

I'm new to Diesel's I have a 2003 with a 7.3 in near new condition with only 50K miles on it. I've only had it for 6 months. It runs beautify, no issues at all. The only strange thing is I have a SCT Livewire which can monitor the engines sensors. My Engine coolant temp reads all over the place as low as -2,200 degrees. While it's cold up here in the winter I doubt it's gotten down to -2200 degrees. Sometimes it reads high 240 degrees before the engine has even warmed up. My dash gauge reads normaly, so the dash guage appears to be accurate. I tried swapping out the sensor, but no effect. Perhaps I replaced the wrong one? Are there two? Perhaps this is a SCT problem and not an engine problem at all. Again this thing runs awesome no issues other than the reading on the SCT and some poor fuel economy. The Fuel economy issue may not be a real issue as I don't really know what to expect for fuel mileage, but I only get 9-10 MPG out of this thing. My "Commute" is only 2.5 miles and I use a remote starter to warm it up. It probably spends as much time warming up as it spends driving to work. When I drive I don't beat on it, but I do like the feel of the power no doubt I could improve mileage by changing driving habits. It still gets way better mileage than my old '82 with a hot 460 gasser and a much better ride.

Just wondering if the Coolant Temp sensor could be making this run extra rich and harming my fuel economy?

Thanks!

[NoRalPh]

It's nothing to worry about, I don't know the details but as I understand it, the OBD-II port info for water temp kind of "floats" (has to do with the configuration I suppose) and isn't actually reflecting what the PCM sees. I saw this too on my AutoEnginuity and was concerned, they say on their website those readings are not to be considered

[2003_F350_7.3_Diesel]

Thanks,

I was kind of hoping that fixing this sensor would improve my fuel milage, but given that the truck runs so perfectly I doubted it. I do love this truck, but its a diesel addict. My best fuel mileage has been 16 MPG on a mostly highway run. The SCT tunner just made the mileage worse, but the power increase is amazing!