Rad fan turns on after ign off timeout

DivineChaos

Veteran Member
Joined
Jul 27, 2019
Location
Minnesota
TDI
mk6 jetta sportwagen tdi
Here's my 3L dramafest chasing that mofo down.....
Well the one in the head should read operating temperature. And the one in the coolant line will read below operating temperature until the thermostat opens. And it may have only been reading weird because I was using obd11 instead of vag com. I have a sensor with me in case it goes out. But I don't know how much I trust a import direct sensor
 

TurboABA

Veteran Member
Joined
Jul 24, 2010
Location
Kitchener, ON
TDI
RIP-2010 Jetta 6spd 2014 Touareg Execline
Well the one in the head should read operating temperature. And the one in the coolant line will read below operating temperature until the thermostat opens. And it may have only been reading weird because I was using obd11 instead of vag com. I have a sensor with me in case it goes out. But I don't know how much I trust a import direct sensor
If you had read my troubleshooting, you would've seen that it's unclear what each of the sensors does or where it sends the signal to. The ecu seems to combine readings and do weird things that don't seem to be documented. If you suspect your sensor is the issue and don't want to do readings off each of them to compare, try unplugging one of them and see if your symptom changes, etc.
 

DivineChaos

Veteran Member
Joined
Jul 27, 2019
Location
Minnesota
TDI
mk6 jetta sportwagen tdi
If you had read my troubleshooting, you would've seen that it's unclear what each of the sensors does or where it sends the signal to. The ecu seems to combine readings and do weird things that don't seem to be documented. If you suspect your sensor is the issue and don't want to do readings off each of them to compare, try unplugging one of them and see if your symptom changes, etc.
I'll have to check the variance between them when I'm home where my veg com is. What baffled me is that it did it whether the vehicle is hot or cold after the ECU timed out. And it happened to me before when I was stage 2. Also during the winter. I just never realized that was why my battery was dead. Cuz I had come out to my vehicle a couple of times with the battery flat. And then I caught it doing this winter
 

fillupamerica

Member
Joined
Nov 12, 2020
Location
Mesa AZ
TDI
2010 sportswagen tdi
Earlier DivineChaos mentioned that a coolant leak may cause the fans to run. I did just notice that I have a small coolant leak just below the coolant reservoir. It looks like it's above the thermostat house area. I'll check this out.

I did get the timing belt and thermostat done at the same time I got the tune/delete.

I wonder. Could it possibly be this?
 

TurboABA

Veteran Member
Joined
Jul 24, 2010
Location
Kitchener, ON
TDI
RIP-2010 Jetta 6spd 2014 Touareg Execline
So when\IF you're actually troubleshooting a system, it is assumed that there are no other faults or issues.....
If you have coolant loss and\or leaks, then fix those before you try to figure out sensors, etc.
Same goes for wires, connectors, etc.

Get some tools and read values, or just start throwing parts at it and pray.
Lots of thing could be causing lots of stuff.....

Special Notes
  • Check the stored Freeze Frame data with this fault code. Freeze Frame information will be found in the fault code description (if the module supports it) or in Generic OBD-II if the vehicle complies with those regulations.
    • Freeze Frame data stored at -40*C is generally an indication of a faulty ECT or wiring.
    • Freeze Frame data stored at +140*C is generally an indication of a faulty ECT or wiring.
    • Freeze Frame data stored with in the 68*C ~ 80*C range is an indication that the vehicle was close to, but not within, the cooling systems normal operation range. The Thermostat itself or Cooling system components may be at fault.
Coolant temp sensors can't measure the temp of imaginary coolant.... if you have coolant sloshing around they will have inconsistent readings.... if you have air pockets or poor coolant circulation, you'll get wachy behavior.. if you have flaky connections, same thing....

If you want to fix it, get some data.... read values, log values, pull codes.... not all malfunctions will store a code... sometimes the ECU will sub something else that's available and will use that especially if the signal is intermittent and it resets after a few cycles, etc.
 

DivineChaos

Veteran Member
Joined
Jul 27, 2019
Location
Minnesota
TDI
mk6 jetta sportwagen tdi
Earlier DivineChaos mentioned that a coolant leak may cause the fans to run. I did just notice that I have a small coolant leak just below the coolant reservoir. It looks like it's above the thermostat house area. I'll check this out.

I did get the timing belt and thermostat done at the same time I got the tune/delete.

I wonder. Could it possibly be this?
Check the coolant outlet flange on the driver side of the block.
 

DivineChaos

Veteran Member
Joined
Jul 27, 2019
Location
Minnesota
TDI
mk6 jetta sportwagen tdi
@TurboABA , @oilhammer , @fillupamerica , @JELLOWSUBMARINE . Alright Malone finally got back to me. Being I'm tun3d as such. First consensus is that water in the back unplugged connectors can flip out the ECU making the car think the exhaust is way too hot and to kick on the fan. I have since looped off all the connectors and insulated the wires. What doesn't make sense to me is this never happened after rain or a carwash. Salt may have done something. They are looking into it.
 

TurboABA

Veteran Member
Joined
Jul 24, 2010
Location
Kitchener, ON
TDI
RIP-2010 Jetta 6spd 2014 Touareg Execline
Skeptical..... what sensor plug is left dangling that the ECU somehow reads and interprets as "exhaust too hot"?
 
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