After a recent oil change I noticed that my 2016 Sorento sxl now will go from a temp gauge of 0 to overheating in seconds even after a cold start and while driving it will be in the normal then bounce from 0 to overheating and slide anywhere along the gauge at any time. Oil level is ok, coolant level is ok, air filter is ok. When this is happening if I shut the car off the fan seems to run high for 10 or more minutes before shutting off. Not sure if I am looking at a failed coolant temp sensor, thermostat, water pump or what could be causing the issue.
Computer should be giving you codes for something. If dash says full hot. For example.
I can give that a shot. I am not seeing any dash warnings and am not getting any diagnostic codes which I find odd.
I have a cheap <$50 scan tool that gives me coolant temp. Does your tool do that?
If this happens even on a cold start, then I’d not suspect anything about stuff like thermostat or water pump. Even with either of those malfunctioning, I can’t think of a way you’d get that much heat right after a cold start. A messed up temp sensor is a whole different story, and I’d think of starting there.
As noted, if you do have any manner of even basic car scanner it will give you what the computer “thinks” the temp is based on the temp sensor readings. That’s worth a look, though I’d guess the gauge is going from that same reading, so it might tell you what you already know - that the computer “thinks” the temps are doing what you see in the gauge.
If it were me, after looking at the scanner readings, I have an infra-red thermometer and I’d likely run the car while measuring the temp of the thermostat housing (or even the upper radiator hose - the reading doesn’t have to be exactly right - all you need to find out is whether or not it’s fluctuating the way the gauge thinks it is).
I think this car uses a pressurized radiator cap with a non-pressurized overflow tank. If that’s the case, out of curiosity, with the engine running do you see any bubbling going on in that overflow tank?
If it does that when the coolant is cold, when you can be pretty sure the coolant isn’t overheating, and most likely there’s a problem with the temp sensor or the display or the wiring. Don’t presume it isn’t overheating though at the other times, there may be more than one problem.
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Live Data is your friend… You can also Google how to test coolant temp sensor…
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Also buy an infrared temp gun. Allows you to check the temp of the radiator, thermostat housing and hoses to find the actual temperature of the coolant.
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+1
They aren’t really expensive, and can make a good addition to one’s tool chest.
You might have an air pocket in the cooling system near the water pump. When the coolant is cold, it doesn’t reach the pump’s impeller. When it gets hot, it expands and reaches pump which then circulates the coolant causing the temperature to drop.
Air pockets? Temp gauge reads hot in seconds after start. It is not a coolant issue. It is electrical.
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And, they work great to check the temperature of your frying pan before throwing an expensive cut of meat on there.