2009 Jetta thermo fans not running - throttle body codes EPC fixed

**Black tsi** · 20-10-2018, 11:44 AM

Hey hey all,

Recently noticed that my thermo fans weren’t coming on.

i always drive with the climate control on, which operates the Themos on a low speed so it took me a little while to figure out.
ive been having intermittent issues with it throwing codes related to the throttlebody that had me stumped.
yes I had replaced the throttlebody and to many other things to list without becoming overly passionate about the situation!

short version, the issue still arose.
I had a short term work around where I would disconnect the 3 electrical plugs near the throttle body (one for the throttle body one is the air temp sensor, one is connected to the canister vac line.)
this would short term fix the issue until I got home and pulled it all apart again.
(Long version available should you want more details.)

I recently disconnected the air temp sensor (above the throttlebody) with the car running, and the thermos started up after a few seconds and went high speed. When it was reconnected the thermos turned off. The engine temp was at a point in which it should have some thermo action.

At that moment it hit me that I haven’t heard the high speed thermos for a long time.
I turned the ac/ climate control off (low speed fan) and the fans stopped all together.
I took it for a quick “wake up thermos” drive, nothing... had it sitting at idle for 5-10 mins, still no thermos.
quick test of the ac again, slow speed thermos come on.
disconnect the air temp sensor, high speed thermos.
car turned off, no thermos after car is shut off.

Firstly I changed out the air temp sensor. ALL my throttle body related codes have disappeared and haven’t popped back up... yet.
Ive done 400kms roughly without hiccups, coughing, Hesitation, EPC lights etc coming on.
knock on wood that has fixed that issue.

I found a decent condition at my in laws wrecking yard to swap out and it’s doing the job for now until I can my new one.

I have checked the fuses, they are all good.
I’m not sure why the high speed thermos function without the air temp sensor plugged in (I haven’t tried the same test with the new sensor in) but the thermos still don’t kick in with the new air temp sensor.

it would appear to be a diff issue.
I recall a while back after a spirited drive, the thermos would kick be audible when you pulled up or switched the car off.

As previously mentioned I always drive around with th ac/climate control on, so the slow speed thermos are always on, but it would be nice for my thermos to be working the way they should be, and for the high speed to kick in .

Any suggestions?

I can’t express how many headaches the throttle body codes and epc issues had caused, so many hours sunk into troubleshooting, cleaning, replacing. I’ll try to find the codes later and add them in here, the air temp sensor was never mentioned in any other possible troubleshooting I read online anywhere, yet this was the missing link to get those issues resolved.

now to get ther thermos happy again.
any help is much appreciated

**Black tsi** · 20-10-2018, 11:56 AM

Codes: 545
Angle sensor for throttle (G188 )

Code: 289
Throttle Position Sensor (G69)

they were the main codes I was getting. Triggering EPC, dodger idle, stalling etc.

These ones were occasional
code: P0221
Throttle/Pedal position sensor

P0121
Throttle/Pedal position sensor

Hopefully these help someone in the future getting a similar issue and may consider the air temp sensor as a possibility.
They aren’t expensive and could save you lots of fluffing around, quoted $100 from VW, $50 from a wrecker, 10-20 online.

**JustCruisn** · 22-10-2018, 09:06 PM

My fans are not coming on. Noticed AC would not blow cold until the car was moving.
Did output tests with VCDS and they do work but never trigger with AC.

Reading your experience I might try unplugging the air temp sensor and see if they come on. I think that could be a good work around, having them run all the time would fix the AC and stop the compressor from overheating.
I think the proper fix is a new set of fans, seems the big fan has a controller that can go bung and wont listen to the AC switch, but will listen to the temp sensor.

**Black tsi** · 26-10-2018, 04:56 PM

Hey Just cruisin,

When I had the temp sensor disconnected, the car munched fuel hey. I was driving gently and it was drinking the fuel as though I was thrashing it hard.
The fans were on high speed which was amazing, good to know the engine was getting cooled as much as possible. But just a warning if your fuel consumption goes through the roof.. you know why.
The defualt setting must not be overly conservative.
oh and it will keep the check engine light on but that didn’t phase me, given the headaches over the last year with EPC and engine light on I’m almost use to seeing it on now. Lol.

wouldnt hurt in your case to try to find someone with a set of fans you can plug in to see if that fixes your problem. Before you shell out for a new set of fans.
Good luck bud

**JustCruisn** · 27-10-2018, 09:02 PM

Hey thanks for the tip.
I kinda thought messing with that temp sensor might cause other issues like you said. And I really don't know which connector it was anyway.

Today I pulled the fans and wired in a relay to the small fan. Now runs based on ignition. It only goes flat out however.
I have noticed from the couple of trips since that the large fan cycles a lot more often than it did before, I'm wondering if the car now thinks the small fan is not there so tries to make up for it.

I'm going to pickup a new fan controller, maybe when I'm in the states at Christmas as I cannot see anyone in OZ selling just the controller.