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Discussion Starter · #1 ·
Hello,
I've got an S5 2017 3.0 tfsi. For the past month it has had issues with intermittent overheating. At first it was just the warning that was coming up, but now temp goes up before warning.
Changed coolant solenoid valve, water pump, auxiliary water pumps, thermostat, temp sensors and bled and vacuum the system properly. Recently, the heating has stopped working as well.

In the days that it happens, the radiator and the expansion tank are cold, no obvious overheating. When the car works fine, both the tank and the radiator are hot...

Wondering if anyone has had this issue before as I am out of options...
 

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If it happens when rad and tank are cold, this is a thermostat problem, but also could be a pump issue. It has been know that the solenoid valve can go bad, but you have changed all these, so I don't know.

Did you change the parts yourself? Have you run diagnostics on it?

I have a B8.5 so it is slightly different on the cooling system, but I know it has electric pumps and a main belt driven pump. The main belt driven pump is also vacuum operated to increase mpg so will only operate when needed. Not sure if the main belt driven pump is vacuum actuated? But the electric pumps should pump enough.

Does sound like a small part that does some sort of actuation, hence it being intermittent but working fine when it's working. I would see if you can get a manual which has all the cooling parts and actuators, solenoids etc to see if you haven't replaced them/it.
 
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Discussion Starter · #3 ·
Nothing coming up on the diagnostic. All parts have been changed by a mechanic, water pump was the only part that was changed at home. Apparently there is one more vacuum valve, that and the ecu turn on the active water pump. I’ve read everything from Erwin regarding the cooling system and the actuators within. I’m completely lost. Taking it at Audi on Monday to get a diagnostic, hopefully I’ll have some answers then… thank you!
 

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NO NOT THE OFFICIAL STEALERS unless you like being ripped off!!!! Find an independent VAG specialist and go to them!!!
 
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