Rad fan turns on after ign off timeout

DivineChaos

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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

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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

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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

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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

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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

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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

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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

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Skeptical..... what sensor plug is left dangling that the ECU somehow reads and interprets as "exhaust too hot"?
 

DivineChaos

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mk6 jetta sportwagen tdi
Yeah. Hasn't happened again. Not sure what's causing it.

As memory serves, the first time it happened was before all my stuff fell off. So them saying a disconnected and coded out wire could cause it.... I'm skeptical.

it hasn't happened again. So I have no idea. I'm not the only person with this issue. It's rare. But it's gotta be something in the coding.
When it happens and I turn the ign on, the fan kicks off. So something is Telling it to turn on....
 

DivineChaos

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Anyway. @TurboABA I do appreciate your help. Not sure what's causing the issue. Seems a phantom issue. Loose wire somewhere maybe? I'll have the temp sensors replaced while the tstat is being done. Maybe it randomly stops working? As it's when the ign is off, idk how to eved diag it.
 

TurboABA

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If you are suspecting or being told that whatever sensor is causing this, log the output from that sensor. So if it's a temp sensor for example, log the temp readings to see what they are when your fans kick in. If it's coolant sensors, you can also log oil temps in order to see if they are inline or totally out of wack.
 

TurboABA

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Are you sure your O2, EGT, and pressure sensors were "re-installed" back properly after those other parts fell off?
Also, if you log all those sensor signals, you should be able to see if you drop the signal from one of them due to a flaky connection or something.
 

DivineChaos

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mk6 jetta sportwagen tdi
Are you sure your O2, EGT, and pressure sensors were "re-installed" back properly after those other parts fell off?
Also, if you log all those sensor signals, you should be able to see if you drop the signal from one of them due to a flaky connection or something.
I've been watching things as I drive and all seems normal. All the other sensors are unplugged so those should cause an issue all the time if it were that. Wouldn't it? Also I don't have an oil level sensor. So no oil temp.
 

DivineChaos

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mk6 jetta sportwagen tdi
I don't know what parts or how they fell off what you're driving, but when I look at similar "failures" I'm lead to believe that some sensors should still be plugged into something.... have a look. PG19 sec 30
As for what Malone told me. All that needs to be plugged in is the egt in the manifold, and the first wideband right off the turbo. The 3 other temp sensors, the pressure sensors, rear o2 and exhaust valve remain unplugged. Along with both EGR.
 
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