P0480 Coolant Fan Electrical Malfunction

Welcome Ladies and Gentlemen, its been a little while since I've posted.

So currently, I'm having the issue of the constant fan running during Key ON, Accessory, and Key Off situations. Now my first inclination was "Crap, I need a new ECU" but being that I have a 2008.5 MKV GTI, Never once has my ECU been opened to flash. Which leads the question, what the heck is going on?

I've already changed my battery since they ran it dead. But the fans do at one point cut off. I'm assuming this is when the CAN system goes to sleep after a few minutes or so when the vehicle is turned off.

The following activity has been done:
1) Checked all fuses:
- SA3 50A Is good. I have another one on order just to be sure
- F24 10A is good. I remove it to park, so it doesnt drain my new battery.
- Relays seem good. I'm sure if either R1 or R2 blew, I would have a lot more Codes than just the P0480.

2) Removal of Coolant Fans. They're sitting awaiting replacement from my order of the Primary and Auxillary purchase from ECS. Since the J293 Control Module is located in the primary fan, I felt it was in my best interest to replace it.

3) Radiator Outlet Coolant Temp Sensor. I'm replacing this sensor due to my information I have regarding failure modes of the certain sensor base. If G83 (Coolant Temperature Sensor) fails, the fans will run constantly in setting 1, whatever the heck that means, and it will not throw a DTC, MIL, or run a secondary signal until replacement. My qualm with this is that if that sensor ran different voltage, I'm sure it would pick it up on VAGCOM. If it failed altogether, I'm sure it would do the same.

So until I can replace the fans, I'm at a loss. I have a full Coolant Circuit diagram which tells me what feeds the coupler into the fan module.
1) Power from SA3 Fuse, always on
2) Ground
3) ECU Signal (Yellow/Violet)
4) ECU Signal Power Relay (Blue/Red)

I haven't checked these circuits yet out of respect for time, but I'm wondering if anyone has dealt with this outside of ECU Replacements. It could very well be that....but I need to be sure. My goal, is to replace the temp sensor first while my fans come in. If it fixes it, then I can cancel the order. But I'm wondering if I should ship my ECU to APR just for safe measures?

Does any tuner have insight they can share for MKV Coolant fans running all the time?

Thank you all.

Does your motor have the EVAP solonoid right above the throttle body? There are a couple hoses and a connector that plugs into it. Just a shot in the dark, but the first time I cleaned my valves I didn't plug this sensor ALL the way back in when I put the manifold back on and the fans constantly ran.

But you are definitely on the right track with the coolant temp sensor, as I did have one go on my MK4 and the fans constantly ran. I would guess it's either that or the J293 module on the fans.

*****2.0t said:

Does your motor have the EVAP solonoid right above the throttle body? There are a couple hoses and a connector that plugs into it. Just a shot in the dark, but the first time I cleaned my valves I didn't plug this sensor ALL the way back in when I put the manifold back on and the fans constantly ran.

But you are definitely on the right track with the coolant temp sensor, as I did have one go on my MK4 and the fans constantly ran. I would guess it's either that or the J293 module on the fans.

Click to expand...

Thanks man. I will check that out tonight.

It appears the $20 coolant sensor was just the thing. Popped it out, put it back in in less than a minute.

I put the car in accessory and the fans did not cut on. I checked the coding and sure enough it had cleared. I put the car back together and cranked it up. No codes. Took it for a drive. No codes.

I guess it's gone. I'll keep an eye on it, but I believe it's gone. Thank God for the Vaglink technical document. It tells you the failure mode of all sensors. I wouldn't have been able to fix this problem without it.

Spoke too soon. Had another failure.

I'll be getting intimate with my multi-meter and fuse diagrams tonight.

I'll feedback