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Audi A4 B6 (2002-200?) Fix for Airconditioning stuck on ECON mode (Replace High-Pressure Sensor/Thrust sensor G65)

I am no mechanic, not even close, but after a spout of successful self fixes on my Audi I thought I would post this, purely because when I was going about trying to fix this particular issue myself there was about 100 slightly different versions of solutions on google, of which a lot give misleading/confused advice. I figured as I fixed it I would take pictures in case it worked, and it did, so hopefully this post will be of use to you if you are in the same boat. Of course as I am no mechanic do this stuff at your own risk, in my case it was my last resort, the garage had no clue and the air-con man wasn’t sure!

So the symptom is the climate control getting stuck on ECON mode, the light stays on and whatever you do, this is how it happened in my 2003 Audi A4 B6 (1.9 Tdi sport), but apparently even same year models can have no high-pressure sensor, in which case it may be your regulator/compressor and a bigger price tag to fix.

Things you will need to fix: Patch Cable from ebay (sub £10), Laptop, VCDS Lite (Free), Torque bit wrench kit, 17mm spanner, replacement high pressure sensor (also called thrust sensor) and about 20 minutes.

First thing I would recommend is getting a patch cable if you haven’t already, you can get these off ebay for a few quid . Getting VAGCOM (VAG = Volkswagen Audi Group) to work can be a nightmare in itself but I would say your easiest (budget) way to get it up and working is to buy a usb patch cable (blue plastic most common) and then download VAGCOM Lite – its called VCDS-Lite, but it is essentially VAGCOM but tweaked down in what it will do, the best bit is its free and with these dumb patch cables it works out of the box. VAGCOM by the way is a software which reads/writes to your cars ECU, it does a lot but all you need it for here is to read/clear fault codes. Anyway there is plenty of good advice about VAGCOM / VCDS-Lite online, so google it, in this case load it up, test it and then go to “select control module” and click “08-Auto HVAC”.

If all is well you will be prompted with a beep from the Audi and a few options on VAGCOM. Click “Fault codes” and you might get a few, what you are looking for here is the following fault code:

High Pressure Sensor (G65)

29-00 – Short to Ground

At first I got this and a few others, complaining about relative problems with the AC system, if you google this you will get a lot of ideas of possible fixes. A Lot. In the end the majority were right for me, replacing the High Pressure Sensor fixed it as well as the other fault codes.. If you are in the same boat then the following is the steps I took to solve it, if you have a bunch of other codes, maybe check with a professional (which might be worth it anyway – see next few steps.)

1. Order the part at an Audi dealership. I recommend doing this before anything else as it might take 24 hours to get it in. Some people have told me they should be called ‘Audi Stealerships’ but in my situation the ability to take my car registration and then pull up a full parts list for my car was invaluable, it let me know that I was getting the right part. I am sure you could get it cheaper elsewhere though, if you are sure of the part.

2. Get system emptied, vacuumed and regassed by a professional. Note you can do this before or after replacing the high pressure sensor. I paid £50 to a local mobile specialist who did this after hours, you can do it yourself, vacuums arent to much etc, but I would get it done properly.

3. Open bonnet, use torque bit (size 17?!?) to take off the offside headlight unit (drivers side for left hand drive cars, a confusion because reading audi fixes on european VWAudi forums state drivers-side meaning UK passing side) – it has 4 bolts, one plug to unplug and then comes out easily.

4. You should instantly be able to spot the high pressure sensor, built into the gas system to the right of the condenser (see red circle in pic.) Unplug its connector.

5. Unscrew the top screw of the plastic moulding between the condenser side and the high pressure sensor, then bend it to the side a little, to give yourself some room to get a spanner into play. A 17mm spanner to be precise.

6. Two or three careful turns should have the sensor loose, carefully unscrew it leaving the rubber o-ring in place. Replacing it with the new sensor and tightning it up carefully but not excessively, it should end up with the clip for the cable conveniently facing. Quality engineering that is, by Audi.

7. Clearing the codes with VAGCOM and starting up the car, you should now be icy cold.

8. Don’t forget to plug it back in, screw up the plastic mount and replace the headlight unit!

If this fix didn’t work for you, you may have bigger problems!

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28 Comments

  1. laik
    Posted March 9, 2012 at 1:36 pm

    how much coste thrust sensor

  2. Posted April 30, 2012 at 7:52 am

    Hi Laik, like £35 GBP or something…Can’t remember now. Is an Audi dealership part.

  3. scott
    Posted June 20, 2012 at 9:34 pm

    Hi woody, this is what i need to do to my car. Where did you get the sensor from? If you got it from Audi, how long did it take to arrive?

  4. scott
    Posted June 20, 2012 at 9:36 pm

    Sorry Woody, the answers to my questions are in your post. My bad

  5. Posted June 21, 2012 at 9:04 am

    All good Scott, Best of luck solving it!

  6. Max Autobrake
    Posted June 22, 2012 at 3:16 pm

    Have been searching the net for advice as I have a very similar problem on my B7 2005 A4. Thanks for a really helpful article and good of you to have gone to the trouble of publishing it.

  7. Posted June 22, 2012 at 3:30 pm

    No worries Max hope it helps.

  8. Markus
    Posted August 8, 2012 at 4:58 pm

    Thank you so much for this terrific guide!

  9. Posted August 24, 2012 at 8:52 am

    No worries Markus!

  10. michel antonios
    Posted December 26, 2012 at 5:41 pm

    i buy another new pressure sensor with 4 pins but they told me that should be Same serial number to be matching with the car computer it is true audi a6 model 2002

  11. michel antonios
    Posted December 26, 2012 at 5:42 pm

    the one i have is for Audi A6 2001 with four pins also

  12. Posted January 7, 2013 at 8:03 am

    Hi Michel,

    Not totally sure, sorry!

  13. moses
    Posted April 30, 2013 at 9:54 am

    how many pins does dat pressure switch have,i hav the same problem

  14. Glen
    Posted May 5, 2013 at 10:42 am

    Hi pal,my ac never worked since buying the car but noticed when replacing cambelt the sensor was missing and the plug was just hanging there!
    I’m going to get a new sensor and try a regas to see if it works but where the sensor screws onto the ac rad there doesn’t seem to be a valve core in the middle like on car tyre valves, did yours have a valve in the pipe or was that why u had to degas it as I’ve replaced these on other cars and didn’t have to degas due to where it screws on is like a tyre valve with a core not allowing gasses to escape?

  15. Posted May 8, 2013 at 2:10 pm

    Not sure Glen/Moses – this was a while back now – I think I was just going on an Audi forum’s advice with the degassing – mine had none in anyhow :/

  16. Moto377
    Posted June 27, 2013 at 10:36 pm

    OK Woody I have the same exact problem, I have a 2003 Audi A4 1.8T Quattro. I just got my AC recharged, vacuumed, check for leaks and it took 1.5 bottle etc. It still blow hot air and my Econ light wont shut off the AC guy at Jiffy Lube had no answer. SO i saw your posts and wanted to see if my High Pressure Sensor was attached so I took the light off and fight the sensor and its was on so I tried to take it off and it like blow up….all this vapor came out and freaked me out. Here’s the worst part as I’m putting it back on the nut on the AC Radiator snapped off and now I can’t put the sensor bolt back in……so I’m fact right??? What do i do? Can i drive the car??

    Thanks,
    Joe

  17. Posted July 1, 2013 at 1:09 pm

    Hi Joe,

    Sorry dude – totally not sure what’s the best solution for this – seems like you opened it under pressure – is probably not as bad as it seems – you might want to ask a professional 🙂

    W

  18. Phil
    Posted July 26, 2013 at 11:29 pm

    Hi mate, I am looking to replace this sensor on my car because VCDS is flagging up the same problem with yours. I noticed that the new sensor looks a lot different to the original. I took my one out and it looks just like your old one. I have found this one on Ebay:

    ebay.co.uk/itm/Genuine-OEM-Air-Con-Conditioner-Pressure-Switch-Audi-A2-A3-A4-A6-Allroad-Q7-TT-/151087149025?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item232d7eefe1

    And it looks like neither the ones in your post. So I am reluctant to order. The part number of mine is 8e0959126 which matches the one on Ebay so I’m really confused! Any help appreciated 🙂

  19. Posted July 29, 2013 at 11:43 am

    Hi Phil,

    Mine did look like that part on ebay, though this was years ago so I can’t be certain I am afraid 🙂

    Best of luck

    W

  20. jooleeo
    Posted August 14, 2013 at 4:57 am

    THIS WILL HELP A LOT OF PEOPLE TO FIX THAT STUPID PROBLEM FROM AUDI.

    FIXED MINE… (BOW) thanks for this hi value information !!!

  21. Andi
    Posted April 26, 2014 at 7:31 pm

    Thanks for this Woody. Just fixed my Audi today. Took much longer than 20 mins. Couldn’t get the those annoying VW electrical connectors off the headlight! Gave up in the end and left it connected. Cheers from Nottingham.

  22. Posted April 30, 2014 at 11:53 am

    Hi Andi,

    Glad it helped! Well done.

    Cheers
    W

  23. darren mcmanus
    Posted June 15, 2014 at 2:54 pm

    Thanks woody this is a grate help time to crack on an get it fixed

  24. Posted June 24, 2014 at 11:53 am

    No worries Darren, Glad it helped 🙂

  25. Jovan
    Posted July 19, 2014 at 11:09 pm

    He!
    I have the same problem. I replaced the sensor and still the same problem. not nullified advantage over computers. Does this mean that the air would work only after resetting.
    Thank you in advance. Jovan

  26. Posted July 28, 2014 at 3:49 pm

    Yeah, you’ve gotta reset it Jovan!

  27. Irfan
    Posted July 31, 2014 at 11:09 pm

    Hi where can I buy this sensor please thanks

  28. Posted September 8, 2014 at 2:24 pm

    Hi Ifran,

    I bought it from the local Audi dealership @ about £35 I seem to remember, however I’m sure you can get it online!

Woody Hayday

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