Author Topic: Fans running all the time  (Read 303 times)

Offline Dre

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Fans running all the time
« on: October 13, 2019, 03:46:30 PM »
Guys i noticed today when i started my car up that the engine management light. I turned the car off after a few minutes and noticed the fans were on whilst my car was off. I found this strange because the car was cold. I had a look at the engine bay and both cooling fans were running making alot of noise. When i started my car up it got up to temp and stayed at 90 but the fans remained on. Even when i turn the car off both fans keep running for around 5 mins before going off. Any ideas what the issue is and if the engine light and fans running is related?

Offline GVK

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Re: Fans running all the time
« Reply #1 on: October 13, 2019, 07:51:12 PM »
Only a scan will tell you what the EML was on for.

You may have an issue with a coolant sensor causing the ECU to run the fans all the time, but as the temp gauge was working I'm not sure, as I say, only a scan of the engine codes will answer your question.
« Last Edit: October 13, 2019, 07:53:57 PM by GVK »
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Offline OEM+ DUB

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Re: Fans running all the time
« Reply #2 on: October 15, 2019, 11:22:58 AM »
My GTI developed the same fault at the back end of last week - both fans running constantly and a check engine warning light on dash).

A VCDS scan identified an implausible signal from one of the two coolant temperature sensors so I'm in the process of swapping both out to fix and for piece of mind).  Did the most difficult one (front of block, underneath intake manifold, inserted in coolant pipe - needs throttle body intake pipe removing along with alternator/belt and tensioner to access) on Sunday.  Hoping to change the easier one tonight (right hand side of block under HPFP/above gearbox - only requires engine cover to be removed).

Hope this helps.
OEM+ 2005 GTI DSG (high factory standard spec and upgraded with S3 alloy hubs, S3 alloy wishbones, Bilstein B8s and VWR springs by my own hands) owned since 2008 and still loving it!

Offline Dre

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Re: Fans running all the time
« Reply #3 on: October 15, 2019, 07:31:48 PM »
I had a friend scan the car yesterday for fault codes and the following came up.

One of them was about a temp sensor which i decided to have a look at and to my surprise the wire to the sensor was missing.

I would be grateful if someone could confirm if the photo below is indeed the temp sensor and how I'd go about getting it sorted.

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Offline GVK

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Re: Fans running all the time
« Reply #4 on: October 15, 2019, 08:48:33 PM »
As there are 2 coolant sensors on these cars that would ring true to what fault you're seeing.

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Offline FJB

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Re: Fans running all the time
« Reply #5 on: October 16, 2019, 04:11:22 AM »
That is the temp sensor without the wires. The wires come out from a hole in the plastic wiring shield that runs above the sensor and about 10 cm to the left. I think you will first have to locate the wires and then attach to a new plug. 

Offline OEM+ DUB

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Re: Fans running all the time
« Reply #6 on: October 16, 2019, 08:21:29 AM »
Yep, that is the easier one to change that I just did last night.  The wiring for it runs through the loom above it so the tails should be there somewhere...

Note though that when you change the sensor (or repair the wiring in your case), the ECU will not correct the issue of the fans constantly running until you clear the stored fault code.

I changed the sensor last night, started the car, no check engine warning light on but then the fans started up again.  The fans only stopped running the instant I cleared the previously logged fault.  Looking at the measuring blocks the sensor was now showing a sensible and rising temperature reading (as opposed to the -48 degrees when it was faulty).

Hope this helps.
OEM+ 2005 GTI DSG (high factory standard spec and upgraded with S3 alloy hubs, S3 alloy wishbones, Bilstein B8s and VWR springs by my own hands) owned since 2008 and still loving it!