My BFS 2007 has done 54k km. It is double radiator fan version and it just got the issue with radiator fan #2. When I start the engine, no matter the engine is cold or hot, the Fan #2 will kicks in after 10 seconds and runs at max speed, very noisy AND the engine checking light is on the ODO. The temp gauge is always at 200F after a few kilometers and remains same position. I believe this temp is normal.

The Fan #2 runs nonstop at max speed even after turning off the engine. Initially there are only 2 ways to turn off the fan: Disconnecting the battery OR the 50A fuse. However, today I found out that if I leave the fan running after turning off the engine, it will automatically stop after exact 10 minutes.

I tried to disconnect the plug from the output of Engine Control Module to the Fan, start the engine, after about 10 seconds, Fan #2 will run at max speed. This means Fan #2 will run without connection to the ECM, right?

Do you think this is a bad ECM or a bad radiator fan?

One thing I must mention here maybe it helps to investiage better, the first owner lost a key, so I made an extra key and the key making procedure might not be correct and even though both 2 keys can start / stop engine, keyless go features, etc all works fine, however, on the software it doesn't show the status on / off of the key (photo attached), it looks like kessy is have problem. Also, I can't connect to the center gateway, it said "Gateway does not respond".

Do you think this relate to the Fan issue? Can an improper way of making extra key mess up with the software and kill the ECM and result wrong fan control?

 

No one? 😭

 

Do you regularly clean any drains ?
Iam thinking the KESSY system which lives in the front passenger foot well box under the carpet .Is this wet ? It’s messed up can’t tell properly if the motor should be off .Fan modules are not communicating properly with the KESSY ?

There’s a scuttle drain under the HVAC unit .
Theres the Aircon drip pan drains / rubber elbows just above the KESSY box .


Is the car stored outside in the rain ?

 

Hi John, thanks for your help!
I checked the kessy box and it looks good, very dry without any sign of water, however, it still show error, I guess because I made an extra key improperly. I am still wondering if this cause software error, which kills the ECU, possibility?

Today I had chance to take my car to VW dealer and here is the update:

The technican swapped Fan #1 and Fan #2 and it's interesting that Fan #2 ran just fine, it only runs when the AC is turned on, and will be off if AC is off while Fan #1 ran at max speed, just exactly like Fan #2 before. On the software it still showed exactly same error. He said these fans should be ok, now we have to check the ECU.

Shall I / Can I swap two ECUs to test the results?

What do you think?

 

Feels like a softwhere glitch .
We a few senior guys like B wings and PMS to chime in .

 

Yeah my friend who owns a Speed also told me that the Kessy error might cause software conflict affecting the ECU. Hopefully Bwings and PMS could chime in and give some thoughts 😁

 

Hi guys, I never won a lottery but today I think I know the feeling of winning one

I fixed the issue of radiator fan running at max speed. The problem is super super simple but it takes so many effort: The electrical wire (yellow brown) from the ECU to the Fan was broken somewhere causing error "P0481 - Radiator Fan 2 Control Module: No signal/Communication" as stated on my #1 post.

I summary the problem here:
Radiator Fan 2 (Engine fan) run at max speed 5 seconds after the ignition is on or engine on. When engine is off, door is locked, Fan 2 will continue to run at full speed for exactly 10 minutes. The only way to stop the fan from running is disconnecting the battery or the 50A fuse on the e-box fuse.

Initial thought: Bad fan control module.

1st test:
Swap Fan 2 to Fan 1 by swapping their plugs on the bottom of the front bumper. After swapping, now Fan 1 (left side) runs at max speed, Fan 2 (right side) runs normally with AC system.

Conclusion: Fan 2 is not bad as guessed. Both fans are fine. Now it comes to the ECU. One of the ECU or maybe both are not working properly.

2nd test:
Swap 2 Fans back to original plugs and now swap 2 ECUs and scan the system. The error is still the same. Fan 2 again runs at max speed. Now it seems the ECUs are not working properly. At this stage, I am about to accept that I have to replace one or even two ECUs

3rd test:
The technican at VW told me that: "Don't worry, I will check for you the wire from the ECU to both fans, let's see if we have any luck". And he nailed it. The brown yellow wire from the ECU plug to radiator fan 2 is broken somewhere and this cause "no signal / communication" between the ECU and Fan, and I think the principle of engine Fan is that if it does not receive signal from ECU, it will run at max speed to protect the engine from overheat.

And here is the moment when he found the wire is broken, and he use another wire to connnect directly from the ECU to the Fan 2 and it just works like a charm


------
It's really worth 3 days at VW and now the issue is fixed.
Thank you all and I hope this information helps

 

Hello @TungNguyen ,
Did you happen to take pictures of both ends of connections, to pinpoint the wires location ?

I have no fault code "P0481", or any for that matter, but both of my fans run as you described timewise, with the driver side (LHD) at normal speed, while the passenger side is jet engine speed, they both shut down just at ten minutes as you stated.

I am also wondering if by me not having the front bumper installed at the moment therefore the outside temperature sensor is disconnected would play into this...

I guess I will install the sensor to test, today.

Johnny

 

Hi guys! I am so worried. I have the same symptoms with the engine fans turning on at high, loud speeds when I start the car. They turn off 10 minutes after turning the car off. PLEASE HELP! Do you guys have a picture of the wiring, part numbers or any diagrams to show my mechanic?? Do you have any way to contact you guys directly?

 

Hello @TungNguyen ,
Please, if you would, respond to the questions asked .

Thank you !

Johnny

 

Hello Johnny, did you find out any information on this? You mentioned you also had the same issue…

 

​​​​​No, as @TungNguyen never responded, I may check the wiring tomorrow, I will let you know.

Johnny

 

HELLO JOHNNY. I bought an OBD SCANNER AND IT IS SAYING P0480 Fan 1 Control Circuit.

 

Hi. I have a similar issue. The yellow and brown wire from the fan plug 4 pin i think is broken somewhere and need to run a wire from the plugs to the other end. Are both yellow brown wires on both plugs joined and come from the same place or different locations
Can you help me out with info please
Cheers Simon