QuattroMark

OK - so figure this out...... New small fan fitted and spins when connected to 12V as does original big fan. New fan control module fitted - still have the same issue, fans don't work. Even after using a 100 ohm resistor instead of the water temp sender to give a temp of 120 degrees (coolant warning on DIS) fans still do not spin. I can get them to spin, albeit very slowly, by activating OUTPUT TEST in VCDS.

Well this has turned into a double whammy! Got the fan pack off - the small fan does not work with an external PSU - the large fan however does work with an external PSU........which means the control unit is faulty.......

I did think that it could be the motors - but why is there only 2.2 V on the LHS fan and nothing on the RHS - I ran out of time today but maybe tomorrow I will take the whole fan tray out and test each motor with a 12V supply.

While stuck in traffic yesterday for around 45 minutes the temperature gauge hit the end stops and the DIS was showing 'COOLANT'. I turned the climate up to MAX and the fan on full and slowly the temperature came down to its 'usual ' place on the gauge - and stayed there until the traffic started moving again. So today, I left the car idling and sure enough after 45 mins the car overheated but the large (LHS) fan would run very slowly for around 10 seconds and then stop - It would do this every 2 minutes - I measured a voltage of 2.2V while it was running. After letting the car cool down I set about fault finding - The 2 lots of 12V and ground were present on the large 4 pin connector that leads to the fan control unit. I had continuity from the ECU to the fan control unit. I cannot get the fans to run even using VCDS to to activate the cooling fans under OUTPUT TEST. If I disconnect the coolant temperature sensor and bridge the plug with a 30 Ohm resistor, the car thinks its temperature is 100 degrees - but the fans will still not kick in. There are no fault codes showing in VCDS. The fan control unit (J293) was changed 3 years ago due to the fact it was blowing the 60A fuse!! - I suppose it could be faulty, but I would expect a code.

So finally got to the bottom of this! The new genuine pressure sensor (from Audi) was faulty - simple as! changed it for another oe sensor, hey presto, got my AC back! As for the 'missing' air quality sensor....wasn't missing - it doesn't have one. My car came out of the factory with 'basic' AC climate control which doesn't utilise an air quality sensor........it seems that pre my ownership of the car, someone changed the climate control unit for the 'convenience' version, which does utilise an air quality sensor!

In a nutshell....... Air Con stopped working - did VCDS scan, came up with 2 culprits. 00256 - A/C Pressure/Temperature Sensor (G395) 004 - No Signal/Communication Freeze Frame: Fault Status: 01100100 Fault Priority: 3 Fault Frequency: 1 Reset counter: 232 Mileage: 399109 km Time Indication: 0 Date: 2025.09.23 Time: 13:54:56 01592 - Air Quality Sensor (G238) 010 - Open or Short to Plus Freeze Frame: Fault Status: 01101010 Fault Priority: 3 Fault Frequency: 1 Reset counter: 232 Mileage: 399109 km Time Indication: 0 Date: 2025.09.23 Time: 13:54:56 Freeze Frame: Temperature: 21.0 C Changed G395 with a new genuine sensor - no change....... not only that, in measuring blocks in VCDS it was saying the pressure was 51 Bar!! - however, it also said the pressure was 51 Bar WITHOUT the sensor connected!! Did the usual due diligence and traced the LIN wire all the way from the sensor to the climate control unit - full continuity in this cable. I even ran another cable direct from the sensor to the climate control unit - still showing the same issue. There seems to be some debate around if I have G238 air quality sensor - because IF I have, I can't find it!! - It is NOT where it should be, on a bracket on the air blower box ( I remember my Allroad having this) - and to add insult to injury, the wire that should be from the air quality sensor to the climate control is not present in the connector of the climate control unit - it is un populated - so either the electrical drawing is wrong, or I do not indeed have G238. I have seen the exact same issue in other forums - but no one has supplied and answer! Any thoughts?

I get what you are saying - but whatever happens I have to fix the leak on this particular head - and the evidence is there regarding the overrun, so i was thinking it maybe prudent to change stem seals ( and check valves) at the same time considering the amount of stripping down i'd have to do anyway - once that bank is done I would do the other.....the car is an absolute workhorse, close to 200K miles now and it is one of the best Audis I have ever owned - and i'd like to keep her running. best, Mark

Thanks for the replies - Looking closer I think the leak is from the gasket between the head and the cam girdle - the question is.....do I take the head off as well while I am there so I can replace valve stem seals...or better left alone - and then also, do I replace top chain tensioners while it is all apart - This could go downhill very quickly!! Mark

My A6 (AUK engine) uses quite a lot of oil - I removed the undertray to see if I could see where it originated from - the tray was soaked! However, after a week or so of driving and parking overnight there was no sign of oil on the floor but quite a lot on the underside of the car, even though I had received a low oil warning earlier. Its possible it is only losing while driving. While I was doing a service on the car I noticed that the vacuum pump was covered in oil and grime as were the pipes underneath the pump - I bought a seal kit for the pump and fitted it thinking this was my problem.......unfortunately not! still getting oil warning indications. After a little more investigation and removing the whole air intake section i noticed that the rear part of the drivers side block was soaked in oil. Looking at 7Zap there is the rocker cover and a gasket, the camshaft frame and gasket and the head and gasket. Its difficult to see exactly where the oil is coming from, but seeing as though I have no performance issues, water loss, oil in water, water in oil etc I'm thinking (hoping!) that the head and gasket to the block is ok. I don't particularly want to remove the head, however, I have noticed smoke from the exhaust when I hit the gas after cruising downhill using engine braking only - this I think is valve stem seals letting oil pass - I am presuming that the head has to come off to replace the stem seals? Anybody had experience of camshaft carrier and head removal? - thanks Mark

Not sure about the fuse, but I have recently had to replace the siren. Remove the scuttle panels that sit upto the windscreen (1 of the clips to the bottom of the screen) -underneath this on the passenger side (UK car) you will see a box which houses an ECU - it is behind that!! - I had to remove the lid of the box to get to the siren. Mark

Finally got around to this.... Bought DVD navigation drive from eBay - £39.00, bought the power connectors from Audi £6, bought the bits to make a MOST loop from eBay £10, bought a antenna extension cable from eBay £8. Plugged everything up in the boot - removed the last bit of roof lining in the rear and found the unused GPS antenna cable for the sharks fin - turned everything on....hey presto it actually works!!!! - Just waiting for the latest version Nav DVD to arrive. So just short of £60 and an hour of time and i have working Sat Nav. Also just added an original Audi DAB module ( £40 eBay) - now got DAB radio! - got to admit, if you are going to do any mod, i would recommend fitting DAB. Mark

Problem solved!!! It turns out that the alarm horn has an internal battery - which is prone to leaking all over the PCB inside. Took me ages to find it - It was tucked up by the nearside A pillar - behind the ECU plastic box. The only bit you can see is a bolt, the horn itself is completely hidden. Had to remove the scuttle panel, both wiper arms, the windscreen deflector panel and finally remove the lid of the ECU container! Replacement off ebay was £16!! Mark

About 3 months ago while my car was parked outside work - what i thought was the alarm started sounding - It was a regular beep ( about 1 per second) and it seemed to be coming from the RHS underneath the scuttle panel under the bonnet. The beeping went on for about 20 seconds - stopped for 10 seconds and then carried on. No matter what i did i could not stop this. I unlocked the car with the fob - locked the car - beeping still there. It would just not stop. There were NO indicators flashing which i thought was odd considering the alarm was going off. I decided to leave it to see what it did - after about an hour it stopped beeping but the indicators were flashing! when i returned an hour after this episode everything seemed ok. I scanned with VCDS but no fault codes. A couple of weeks later the same thing happened around 7PM - the car had been parked for about 1 hr. Again nothing would stop the beeping - so i started the car up and left it running for about 2 minutes ( still beeping at this time) - turned the car off and locked with the key fob - the beeping stopped. Did another VCDS scan, nothing recorded. Everything has been fine until 1:30 AM this morning! - started beeping - nothing would stop it - tried disabling the interior monitoring ( switches on the B pillar) - started the engine for 2 minutes - hey presto the beeping stopped. Another VCDS scan - nothing recorded! Anybody any ideas? Mark

Had my A6 C6 3.2 FSI quattro for around 6 months now - had a few minor issues along the way....but generally all good. My latest issue, probably something to do with a change in the weather - The HOT/COLD controls seem to be all over the place - if I switch from hot to cold it stays hot for around 30 mins then slowly cools down - if i turn the engine off and leave it for 5 mins then turn back on the blower is cold.....however i have noticed that i can't get cold aircon to blow at all, the air is quite tepid- the system is pressurised it just seems that the temperature will not go low enough. It seems like none of the flaps are working correctly - I can hear them moving, or at least i can hear the motors running - Is there a way of resetting these? And most recently i have noticed that during a long drive, after around 2 hrs the car just steams up- to the point where I have to stop! It will be like this for the rest of the drive.....however leave it overnight and the following morning it is ok - I am not loosing water and there doesn't seem to be any evidence of leaking into the car. ideas anybody?

No DVD unit in the boot - there is only the radio unit..... Been having a look to see which DVD player I need and there are a couple of options....guessing will also need a power split lead and a MOST fibre splitter....