I have a 2018 A7 55 tfsi. I’ve had a new thermostat and water pump recently fitted. If I drive the car from cold within a few miles the fan will start. If I continue to drive I get the warning “coolant level too high” As soon as I stop the fault goes away. If I then drive off it can come back, however if I turn the engine off then restart a minute later I will have no issues for the rest of the day and the fan never comes back on. 
To avoid this, I have resorted to starting the car on the drive and letting it run for 5mins then turning it off and leaving it for a few minutes before setting off. Very frustrating! Any ideas PLEASE

 

Is the level genuinely high when you get the warning? In other words have you looked at the reservoir? Are you having to top up coolant frequently? Did the problem start after renewal of thermostat and coolant pump or before?

The temperature level on the dash is always normal when the fan starts and when I get the warning that coolant level is too high

i have checked coolant level in reservoir and it’s fine and not loosing any coolant

The problem started about a month after the water pump was replaced. The thermostat was changed about 9 months prior to the water pump

One mechanic suggested a solenoid sticking? Does that make any sense?

Welcome Guy, and sorry to hear of your issue. 
As I see it, whoever (garage?) fitted the new thermostat should be your first port of call. 
It could be as simple as air locks in the system, faulty temperature sensor or even a substandard replaced thermostat. 
Ideal would be to get it plugged in to diagnostics to get any fault codes and to record live temperature data.

Please keep us up to date on progress.

Regards,

Gareth. 

Thanks Gareth. I’ve been using an Audi “specialist “ but maybe the time has come to bite the bullet and let an official Audi garage look at it. 
The problem I’ve encountered is that when they plug it in they’re telling me no faults are showing so hard to accurately diagnose the correct course of action. 

Only just joined this forum, posted a question and had two replies from Cliff and Gareth almost immediately. Thanks guys, very impressive 

No problem Guy, it seems our posts overlapped.

So logic would now point to dismissing the thermostat as the culprit, since the car was OK until the water pump was changed.

So water pump associated ( or something else which has gone wrong in the meantime)?

Still air locks, level sensor? Solenoid associated with water pump?? Stevey Y on here would be your best point of contact. Send him a PM and ask him to have a look at this thread - he’s a busy man, so give him a bit of time. 
Why was the water pump changed Guy? 
Others on here will hopefully be along to offer advice. 
Regards,

Gareth.

p.s. Audi main dealer?? Oh blinking heck, your wallet will need gas and air! I’d forget that as an idea, and take advice on other independents in your area. 

 

Hi Gareth. I’m told the water pump has a shroud system which allows the engine to heat up quicker and this shroud works on a vacuum system. Apparently this system is the most common failure when it comes to coolant issues and they told me they tested the old one and it was sticking. 
excuse my ignorance but how do I send a personal message to Stevey Y?
Also, wise words regarding Audi main dealers 😀

 

 

No probs Guy,

I’ve messaged Stevey and asked him to have a look at your post when he has a chance - he’s a busy chap though.

Regards,

Gareth. 

Thanks so much Gareth. I’ll keep you informed on any progress

kind regards 

Guy

3 hours ago, Guy Currie said:

The temperature level on the dash is always normal when the fan starts and when I get the warning that coolant level is too high

I am confused, which happens easily. Are you referring to coolant temperature or coolant level?

Hi Cliff. I’m referring to the temperature level not the level of the volume of coolant (which is fine when looking at reservoir). When the warning of “coolant temperature too high” comes up the temperature level showing on dash is still showing as normal

So the warning is "coolant temperature too high", not "coolant level too high" as you first reported? That's why I was confused.

4 hours ago, Guy Currie said:

Hi Cliff. I’m referring to the temperature level not the level of the volume of coolant (which is fine when looking at reservoir). When the warning of “coolant temperature too high” comes up the temperature level showing on dash is still showing as normal

Hi I think your problem may well be the coolant temperature sensor which will either be mounted on the thermostat housing or on the cylinder head that is what controls the operation of the fan, as far as the water pump being vacuum controlled thats wrong they are thermostatically controlled therefore the thermostat that controls the shroud on the impeller will only command the shroud to move when it is reported to the ECU that the coolant temperature is high enough to move the shroud from the impeller allowing it to circulate the water more efficiently, they very rarely seize in the closed position, that would cause rapid overheating, they usually seize open in which case the car takes forever to get warm in winter months, if you look carefully you will see the control wires coming out behind the cam belt cover and disappearing into the connector for the engine loom, the only real way to check the temperature sensors is with live data diagnostics so in view of the relatively cheap price of the part [dont buy it from Audi] its probably worth taking a punt and replacing it.

Steve.

Hi Steve. Thank you for taking the time to respond. I drove the car three miles to the local supermarket today and the fan came on just before I stopped. I’m pretty sure if I continued driving then I would get the “coolant temperature too high” warning come on. I turned the engine off and the fan stopped. I got back in the car about 10 mins later and drove home with no issues and no fan starting.

I regularly drive 100-200 miles a day in the car. The issue only happens after the initial cold start. Once I turn the engine off and then restart it after a few minutes I can drive it all day with regular stops and starts with no issues. If it was a faulty temperature sensor why do I only get the issue from initial cold start then nothing after that?

 

thanks Guy

17 minutes ago, Guy Currie said:

Hi Steve. Thank you for taking the time to respond. I drove the car three miles to the local supermarket today and the fan came on just before I stopped. I’m pretty sure if I continued driving then I would get the “coolant temperature too high” warning come on. I turned the engine off and the fan stopped. I got back in the car about 10 mins later and drove home with no issues and no fan starting.

I regularly drive 100-200 miles a day in the car. The issue only happens after the initial cold start. Once I turn the engine off and then restart it after a few minutes I can drive it all day with regular stops and starts with no issues. If it was a faulty temperature sensor why do I only get the issue from initial cold start then nothing after that?

 

thanks Guy

Hi they break down over a period of time until they die completely, I can only conclude that it might be at the stage where cold coolant affects its operation until the car gets warm then after its restarted it may well reboot and operate properly, what you have described is classic sensor failure in the making there are probably two coolant temp sensors on the engine one of which works the gauge and the other by a calculation based on the information from the gauge sensor but it can't understand what the gauge sensor is sending it when cold.

Steve.

Hi Steve. Thanks again for your reply. The sensor doesn’t look to be very expensive so definitely worth a punt as replacing. Is this a job for a garage as my mechanic skills are pretty limited?

Hi Steve

Don’t know if this helps but to avoid any issues, I sometimes start the car in the morning and let it run for 10mins then turn it off. Then set off maybe 30 mins later and never have a problem. Does that point towards a sensor issue?

I really appreciate your help and thanks to Gareth for forwarding this to you. 
 

cheers

Guy

20 hours ago, Guy Currie said:

Hi Steve

Don’t know if this helps but to avoid any issues, I sometimes start the car in the morning and let it run for 10mins then turn it off. Then set off maybe 30 mins later and never have a problem. Does that point towards a sensor issue?

I really appreciate your help and thanks to Gareth for forwarding this to you. 
 

cheers

Guy

Hi quite possibly, if you consider the dynamics of the problem it means the sensor has had a chance to warm up, the working strategy for all the emissions related functions are to warm the coolant as quickly as possible then maintain the working temperature within a very tight perimeter to optimise low NOX/HC emissions, lucky its not diesel as your current problem would play havoc with regenerations, at the moment its never going to be terminal, just annoying.

Steve.