Air Con Pressure Temp Sensor location

Hi johno5

Did you ever find a solution to this. I have the same problem with the data bus cable and the above mentioned sensor causing problems (implausible reading I think)

Cheers

Hi all, first post here so trying to make myself useful, rather than just a bid for someone else to help. There's quite a bit of info online about this, (location etc) but a few details missing so I'll share how far I've got.

Background:
A/C didn't work and when I did my yearly service, so plugged in my VAG scanner and was surprised to find quite a few codes...

08 Auto HVAC 00256 A/C pressure Temperature Sensor (G395) Sporadic 008 - Implausible signal
00457 Control Module for network (J519) Sporadic 013 - Check DTC Memory
01592 Air quality sensor (G238) - sporadic 004 No signal/connection
09 Cent Elec 03020 local data bus 2 - sporadic 012 - electrical fault circuit

and some other most likely unrelated door issues.

And whilst searching for answers came across an Audi technical bulletin that sums up our problems (do a google search for 2020124-2, the pdf file titled Air conditioning inoperative was a massive help.

So i inspected the sensor and did not see any corrosion.

Today I took it for a A/C service and recharge at a Halfords Autocenter for £49, and left the panel that covers the sensor off so they could see if it leaked as expected in the Audi technical bulletin (although because of the good condition of the sensor I didn't expect it to leak)...

It leaked

It was hissing from the G395 pressure sensor and so they drained the gas.

They drained the system and now it's back on the drive again. So I've taken it apart to see if it's corroded inside making the most of knowing there's no pressure in it. It's these pictures I hope are useful for others as I've not seen them anywhere else.

These pictures show the valve that sits under the sensor, so it should be safe to change under pressure. It also tries to show the oily residue from where it leaked inside the connector. It appears to have crept around and past some of the pins.

The bumper did not need to be removed. Just required a 17mm spanner. less than 10min job to replace.

So I'm weighing up my options: -

Replace myself (Part from Ebay £30 from china (by part number listed in the technical bulletin mentioned in this post), and then another £49 for halfords to recharge the system. (but maybe it or something else will leak?) all in £79 if all goes well.

Or Audi £61 for the sensor + £3 for new 0-ring. Audi also quoted me £80 for labour ontop of that, and then £79 ontop of that again for the aircon recharge. (get a 2 year warranty on it though) £223 all in, if all goes well.

Halfords will get back to me on monday with their price.

Thats my experience with the problem so far, hope it helps someone. Likewise if anyone has any advice for me or can shed some experience it would be appreciated.

Cheers, Dan

Good write up dude should help us if we get same snag


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Get a new genuine sensor & o-ring and fit yourself, don't be tempted the get the cheap one or reuse the old o-ring, it's surprising how quickly the cost can mount up regassing the aircon system.

For the sensor see if there is a local TPS center near you that could save you a few quid on the parts. You have already removed the sensor so I would not pay the extra £80 that Audi want. Also put the damaged sensor back on while your driving the car around you don't want dirt getting into that sensor socket.

Thanks for that B5NUT. That was my thinking too. Saw the first leak as fault finding really.

It's now fixed. Sourced the new sensor (and new O ring) from Audi for £63. The new sensor differs from the old one slightly. It has a black top and takes a slightly bigger spanner but not problems to fit, very easy. And was recharged no problems for £45 from a garage down the road.

At last lovely cool air!!

For those with the same problem I can confirm that in my case the new part has cleared the codes

08 Auto HVAC 00256 A/C pressure Temperature Sensor (G395) Sporadic 008 - Implausible signal
00457 Control Module for network (J519) Sporadic 013 - Check DTC Memory
01592 Air quality sensor (G238) - sporadic 004 No signal/connection
09 Cent Elec 03020 local data bus 2 - sporadic 012 - electrical fault circuit

Just hope this helps others looking for answers.

Dan

anyone know the part number for the señor and the O ring as mine has gone on my B8 (i think) as i seem to have most of the fault codes you have

I believe the Sensor is 8E0959126B and O-ring 7H0820896. (These parts superseding sensor 8E0959126 and o-ring 8A0260749AK)

To clarify I do not work for Audi or have access to their most up to date documentation. I use http://audi-club.md/etka-online and selected the language then found these via Audi > Audi A4/Avant Europe > 2008 (8E-8-000 001>>) > Fuel,exhaust, cooling > Item 26041 a/c compressor fluid container with connecting parts.

I hope that helps and shows my working, I'm not sure how current that document is but you can make your own mind up. Personally I just phone a dealership so they can quote me a price.

Dan

Edit: Broken link

I had a quick look at the one on my car today, it looks like it has the revised version with the larger hex section, it is a January/February 2011 build for reference.

mine is a 61 plate and the spanner to take it off is bigger than 17mm ?

these are the fault codes I'm getting
ECU info obtained with Carista 300199 for iOS:


Infotainment system

Part #: 8T2035652L

Coding: 010101000106C1ED05000F0E000000030000 (hex)

Component: B-BN-EU

Fault codes:

03276 Testing Management Software version

03175 Invalid Dataset

03157 Function Limitation because of Communication Failure


Heater & air conditioning

Part #: 8T2820043AF

Coding: 34340000 (hex)

Component: KLIMA 3 ZONEN

Fault codes:

01592 Air Quality Sensor (G238)

00256 Givers for refrigerant pressure / temperature (G395)

00457 Control Module for Network (J519)




Central electronics

Part #: 8K0907063N

Coding: 26005091403C8F010001080000001D0D401D230806010141000000 (hex)

Component: BCM1 1.0

Fault codes:

00256 Givers for refrigerant pressure / temperature (G395)

01592 Air Quality Sensor (G238)

Adam, I think this component has given them lots of trouble in the past and keeps getting modified to rectify it. (They appear to be on their fourth modification of that component)

Yer sorry about the previous number that was for a 2008, the one below is for 2011. You must have one of the modified one's already, as I said in an earlier post it took me something larger than 17mm to install the new one, even through the one that came off was 17mm.

One hint I can give that I didn't say before was once halford drained the gas, (because it leaked the first time they filled it, before I changed the sensor), the reservoir is full of air. If you let everything cool down overnight, and then drive for about 20mins the next day, when the air inside gets hot/expands you can put your ear to the sensor and in my case hear it leaking.
I noticed this because I drove it like that to Audi to get the part.

That may confirm for you wether it's that sensor or something else giving you problem. It should still do that with whatever is left in the reservoir too.

Dan


Image of modified 2011 components:

@shermand100 i can't seem to zoom in to get the part numbers please could you post them ?

Sure:
Item 4 - Pressure Sensor 4H0959126
Item 3 - O ring 7H0820896

Oh bother, so having a newer version does not sort this, bother, bother! I'll need to charge up my AN134 sniffer and poke it through the front grill to see if it can sense any gas leaking.

fitted the new sensor today, went to get it toped up they told me it was far far overfilled not to turn on my AC as could blow :/ and to seek special advice ? anyone ? possible problems ? also my Ac pump isn't engaging apparently

Well now you need to get a proper air con person to recover the entire charge and note its weight, then refill with correct weight of R134A. If Kwikfit etc have overfilled it then give them the bill?

i have now replaced the sensor but the fault won't clear took to a place to have refilled today and they said that the sensor is the problem although i have only just replaced it ??? anyone have any ideas its a 61 plate wouldn't have thought the technical bulletin applied to mine as it was early 2010 ?

rum4mo said:

Oh bother, so having a newer version does not sort this, bother, bother! I'll need to charge up my AN134 sniffer and poke it through the front grill to see if it can sense any gas leaking.

Click to expand...

No, I've checked might with a sniffer and nothing detected - so far so good!