S5 B9 intermittent overheating

3077 Views 15 Replies 6 Participants Last post by SWS%, 2 mo ago

Bia

Discussion Starter · 11 mo ago

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...

Reactions: 1

1 - 16 of 16 Posts

Dave Kwatro

· #2 · 11 mo ago

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.

Reactions: 1

Bia

Discussion Starter · #3 · 11 mo ago

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!

Reactions: 1

SimonRoma

· #4 · 11 mo ago

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

Bia

Discussion Starter · #5 · 11 mo ago

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

Managed to fix it at home. It was the valve that vacuum stops the water pump…

Reactions: 1

Dean-walsh

· #6 · 9 mo ago

Bia said:
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!

Bia said:
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...

Hi. Did you get to the bottom of the overheating problem after taken it in to the dealers. I’m having the same issue

Bia

Discussion Starter · #7 · 9 mo ago

Dean-walsh said:
Hi. Did you get to the bottom of the overheating problem after taken it in to the dealers. I’m having the same issue

Hello,
I fixed it at home. It was the coolant pump switching valve that vacuum stops the water pump. It’s really cheap and easy to change.

Dean-walsh

· #8 · 9 mo ago

Bia said:
Hello,
I fixed it at home. It was the coolant pump switching valve that vacuum stops the water pump. It’s really cheap and easy to change.

I’m so glad you said that lol. I’ve just changed mine over fingers crossed it’s that on mine

Reactions: 1

jpala

· #9 · 8 mo ago

Bia said:
Hello,
I fixed it at home. It was the coolant pump switching valve that vacuum stops the water pump. It’s really cheap and easy to change.

Do you have the part number for the coolant switching valve? I assume that is located at the other end of the only rubber hose on the water pump? I am having a similar issue as well.

Bia

Discussion Starter · #10 · 8 mo ago

2

jpala said:
Do you have the part number for the coolant switching valve? I assume that is located at the other end of the only rubber hose on the water pump? I am having a similar issue as well.

Hand Finger Gesture Thumb Wrist

Motor vehicle Automotive tire Font Auto part Automotive design

See less See more

jpala

· #11 · 8 mo ago

Thank you so much for the quick reply! That diagram is perfect and luckily the part is easy to find and even better easy to get to. Thanks again. From what I could read on the last partial page you included it sounds like that part keeps coolant in the engine to allow for quicker engine warm up. Then opens I assume the N649 Mech coolant pump switch is the same thing as the "coolant shut-off valve"? If so this should fix my issue. Thanks again.

Bia

Discussion Starter · #12 · 8 mo ago

2

jpala said:
Thank you so much for the quick reply! That diagram is perfect and luckily the part is easy to find and even better easy to get to. Thanks again. From what I could read on the last partial page you included it sounds like that part keeps coolant in the engine to allow for quicker engine warm up. Then opens I assume the N649 Mech coolant pump switch is the same thing as the "coolant shut-off valve"? If so this should fix my issue. Thanks again.

Hello. No worries. It should. However, the coolant shut off valve is the attached. Hope this helps.

Automotive tire Personal protective equipment Gas Glove Sports gear

Font Art Auto part Motor vehicle Illustration

See less See more

Bia

Discussion Starter · #13 · 8 mo ago

jpala said:
Thank you so much for the quick reply! That diagram is perfect and luckily the part is easy to find and even better easy to get to. Thanks again. From what I could read on the last partial page you included it sounds like that part keeps coolant in the engine to allow for quicker engine warm up. Then opens I assume the N649 Mech coolant pump switch is the same thing as the "coolant shut-off valve"? If so this should fix my issue. Thanks again.

Also, just so you know, in case is the solenoid, the N489 Cylinder head coolant valve has the same part number as N649 Mechanical Coolant pump switching valve.

jpala

· #14 · 8 mo ago

Bia, your advise was spot on. The part arrived a few days ago and my issue was the N649 valve. Swapped it out and all is right in the world again. Thanks so much for your help!

Bia

Discussion Starter · #15 · 8 mo ago

jpala said:
Bia, your advise was spot on. The part arrived a few days ago and my issue was the N649 valve. Swapped it out and all is right in the world again. Thanks so much for your help!

No worries. Glad you managed to fix it. I know how stressful it can be 🤦🏻‍♀️

SWS%

· #16 · 2 mo ago

Bia said:
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...

Hello, Thank you for this info!
I have a similar issue. 4 months ago I got the low coolant shut engine off warning. After seeing good coolant level I replaced the coolant tank with senso,r went on a short test drive light came on and car began to get hotter than normal so I turned on the heat and shut off the engine before it overheated. Got it home and changed switching valve N649 and the light went out.
2 weeks ago the light came on during a 5 minute drive. Took it to the dealership, the insisted is was the coolant reservoir then the wiring to the sensor in the reservoir, both diagnoses were wrong. Now they say it may be the comfort module as they say it may be sending bad signal to the dashboard but they say this may not help.
I got on the phone with with the Adui tech and shared the service bulletin about the switching valve N649 and asked him to test it.
My thinking is maybe the shutter in the coolant pump is getting stuck or maybe there is a vacuum leak. He responded "I dont think makes sense to go that route we should just change the comfort module for $2k and if you request to have the N489 and shut off valve checked it would be $3k.
Any thoughts or idea why I may be getting low coolant warning after changing the switching valve a few months ago?
All else fails I may just check vacuum myself and change the water pump, thermostat, shut off valve and both N489 and N649 as this is cheaper than the dealer switching the module and at least I know all components are new.
Thanks in advance for all input

See less See more

1 - 16 of 16 Posts

Top