# P0597, temp gauge is at normal reading, fan runs constantly



## Jen82076 (Nov 11, 2021)

Car has 208,000 miles and generally has been a good car after finally finding and fixing the oil leak. Replaced the valve cover and intake to updated parts. Noticed fan still running at times when I think It shouldn’t and now even more after fixing the coolant leak. New water outlet and hose going to recovery jug. No leaks anywhere. P0597 code immediately comes on. Trying to diagnose problem and took the thermostat/housing out and see that the thing has come apart. Wires have come loose (all kinds of extra wire shoved down in the housing) and, spring jammed so nothing is flowing through the radiator. What’s the point of having the temperature gauge on the car if it’s not going to let you know the car is actually running HOT and a temp of 220 or more (which this one was) is hot to me? It’s a thousand wonders that the overheating didn’t ruin the motor.


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## snowwy66 (Nov 5, 2017)

Those motors run at 220 with a fan kick on of 231.

The second gen motors run at 190 with fan kick on of 212 iirc.


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## Johnny B (Jun 4, 2019)

There is actually a long history behind why most car gages have been either eliminated or dumbed down. To cut down on BS shop visits when the car is under warranty. Sorry for the truth bomb. 
Anyway, IMHO car gauges should not be used for troubleshooting. Use an OBD scanner or don't bother.

Fwiw, my coolant runs at 230F.


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## Bvogt (Dec 19, 2021)

Johnny B said:


> There is actually a long history behind why most car gages have been either eliminated or dumbed down. To cut down on BS shop visits when the car is under warranty. Sorry for the truth bomb.
> Anyway, IMHO car gauges should not be used for troubleshooting. Use an OBD scanner or don't bother.
> 
> Fwiw, my coolant runs at 230F.


so, dont bother checking gages? have a scanner hooked up at all times? gages are the first step in troubleshooting a problem before it becomes a larger problem. I wish cars still came with at least oil pressure gages. boost and egt would be nice too. they are only "idiot gages" if you dont look at them until a code gets thrown or know what they are telling you. with that said, yes, a scanner will provide you with the most accurate readings


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## Johnny B (Jun 4, 2019)

Well, yes. 
This will take a minute to explain, but you asked.

In your case, you want to use the coolant temperature gauge for troubleshooting. Well guess what, that gauge does not give an apples-to-apples readout. Once the coolant reaches about 190F it will stop exactly one tick short of mid-range every time. The gauge will read EXACTLY the same for any coolant temperature between about 190-240F. Why you might ask? To give people that warm fuzzy feeling their car is working perfectly, so they don't take to the dealership and waste everyone's time. This is also why the gauge doesn't have a temperature scale, same reason. Cars ran at 180F for decades, now they run at 210F-ish. And everyone being so in tune with their car might "think" it is overheating now. So 98% of vehicles don't show an actual temperature, at least not on the home DIC screen.

Another common logic gap I see now and then is people don't understand why their car is obviously overheating (i.e. steam rolling out of the engine compartment) and the temperature "gauge" reads normal. Wonder why? Well, it's called physics, unpressurized water can only get to 212F, so if the car's computer needs to see 240F + coolant temperature to activate a warning it will never get there. The real problem every auto manufacturer faces is the average buyer either knows nothing about cars or very little.
One more example, autos with a voltage gauge (mostly trucks), same thing it is programmed to read the exact same voltage like 95% of the time. Why, because alternators are controlled by computers and vary the voltage constantly.

All that said, IMHO most car gauges are there so you can operate it. And maybe prevent you from completely destroying it when there is a problem. And not for troubleshooting.


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## Bvogt (Dec 19, 2021)

Johnny B said:


> Well, yes.
> This will take a minute to explain, but you asked.
> 
> In your case, you want to use the coolant temperature gauge for troubleshooting. Well guess what, that gauge does not give an apples-to-apples readout. Once the coolant reaches about 190F it will stop exactly one tick short of mid-range every time. The gauge will read EXACTLY the same for any coolant temperature between about 190-240F. Why you might ask? To give people that warm fuzzy feeling their car is working perfectly, so they don't take to the dealership and waste everyone's time. This is also why the gauge doesn't have a temperature scale, same reason. Cars ran at 180F for decades, now they run at 210F-ish. And everyone being so in tune with their car might "think" it is overheating now. So 98% of vehicles don't show an actual temperature, at least not on the home DIC screen.
> ...


im in complete agreeance with you regarding real time data. I build high end resto mods for a living. all our inputs are real time, from boost to driveshaft speed to diff temp. i get that gages, most especially on economy cars, are general information for the general driver. with that said, i was speaking more to the effect that if a driver doesnt have a clue about anything automotive (like my wife) comes to you and says "somethings wrong with my car" and all they are able to tell you is that the temp gage was fluctuating or the DIC says to turn the car off due to heat yet the gage was fine, I can diagnostically deduce what system is malfunctioning. thats my long winded way of saying you are right, but believe it or not, idiot lights and ballpark gages are the only diagnostic tools that most people have.


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