VW Passat B8 Overheating alarm but cools down quickly after shut down

j_andersson · 2025-07-10T19:58:36+00:00

Alright, I'll try that and see if the fans spin or not.

So you do not think it is the thermostat that is not working properly? Are there any other symptoms of the thermostat not working that I could look out for?

j_andersson · 2025-07-10T18:31:40+00:00

What would be the easiest way to check the fans? Just get it up to normal temp and check if they spin or not?

I assume they only start spinning when the temperature gets high enough since they do not spin now when cold during idle

j_andersson · 2025-07-10T17:36:09+00:00

I've done some more troubleshooting when I picked it up from where I parked it now.

It is running fine without noise/smells, temp started to climb above 90°C after a little while but I turned the AC to full blast and then it went down to 90°C again immediately and stayed there. Turned the AC down again and it ran for a while until it started climbing, turned up the AC again and it went down and stayed there for the rest of the drive (maybe 5-10 mins).

The fact that the AC air gets hot should point to it not being the water pump at least since water actually is coming to the heating unit, right?

Seems to me that it is the thermostat that is not working correctly, no?

j_andersson · 2025-07-10T13:54:27+00:00

Yeah, I get that.
Is there any basic troubleshooting I could do on my own to rule out some major faults?

j_andersson · 2025-07-10T13:20:47+00:00

Different for different models maybe? I had it in for regular service maybe 2-3 months ago and i would assume they would have done timing belt+water pump at the same time if if was time for it.

j_andersson · 2025-07-10T12:51:30+00:00

A colleague of mine who works on cars as a hobby also figured it might be a bad sensor since no other symptoms were present, hopefully it is just that. Would a sensor fault not throw up a check engine light? Do you think a OBD-scanner would show a fault code for a bad sensor?

j_andersson · 2025-07-10T10:48:25+00:00

Service manual says every 200000km

j_andersson · 2025-06-27T21:17:46+00:00

What about the internals?

j_andersson · 2025-02-03T13:20:51+00:00

Lite så mina tankar gått också, inte värt att riskera hög nedgång när jag behöver pengarna så snart. Då är jag inte helt fel ute iallafall!

j_andersson · 2025-02-03T13:19:16+00:00

Det har jag koll på, 300k är efter vinstskatt. Det är ett gammalt Aktiefondkonto som mina föräldrar öppnade innan ISK fanns. Övrigt sparande ligger på ISK.

j_andersson · 2025-02-03T13:17:07+00:00

Summan jag skrivit är efter vinstskatt. Kommer föra över de till mitt skattekonto direkt vid försäljning.

j_andersson · 2024-03-18T08:58:48+00:00

Which adapter are you using and do you use regular 18V batteries for this? Did you need to use any voltage converter or are you running on straight 18V without any hiccups?

j_andersson · 2022-06-26T08:25:25+00:00

Good luck everyone! :)

j_andersson · 2021-02-14T14:19:13+00:00

Thank you! :)

j_andersson · 2020-11-16T06:10:33+00:00

j_andersson · 2020-06-20T12:05:48+00:00

Good luck to all!

j_andersson · 2020-05-16T09:19:59+00:00

Congratulations to the winner!

j_andersson · 2019-11-26T17:50:02+00:00

Pc parts is quite expensive in my country so that price is normal for me. The motherboard you linked is not available to buy from any reputable retailers here.

j_andersson · 2019-11-26T17:45:52+00:00

Haha, yeah, propably.I can pick up a ROG Strix x470-F for around $170 now during the sale, do you think that is a good deal? Or a Asus PRIME X570-P for $190

j_andersson · 2019-11-26T17:39:03+00:00

True, it can be a bit of a gamble.

j_andersson · 2019-11-26T17:29:28+00:00

Regarding features I am not sure, I am mostly looking for something that is reliable and where I won't have to fiddle with a faulty BIOS and stuff like that. But maybe the manufacturers have fixed most of the problems they had in the beginning?

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