Outside air temperature update

CrispyEdd

CrispyEdd

Member
United-Kingdom
Hi

Is it possible to calibrate the outside air temp sensor in vcds?

Mine over reads by roughly 2.5+ c very annoying
 
I'm, (almost), certain there's no provision for ambient temp sensor calibration.
Check the sensor you have is OEM.
Other than that, beg or borrow another sensor, and compare readings, with sensor in something to keep it at a constant temp, such as water. It must be water proof, given where it is located!
Mac.
 
  • Like
Reactions: Ami
PlasticMac said:
I'm, (almost), certain there's no provision for ambient temp sensor calibration.
Check the sensor you have is OEM.
Other than that, beg or borrow another sensor, and compare readings, with sensor in something to keep it at a constant temp, such as water. It must be water proof, given where it is located!
Mac.
Click to expand...
I'm not a VCDS expert and am reasonably certain that what you've said is correct for the A2 as it is one of the earlier systems that VCDS can work with - however there is an indication in one of the VCDS forum technical posts that some VAG systems at least can give a reading for both actual *and* an adjusted external temperature value - which makes me wonder if the same is possible if you know exactly which adaptation channel to modify to fine-tune the reading (in the same way that I can adjust the fuel tank needle position or other similar parameters in the dashboard).

However - it is not made clear how one would go about effecting the adjustment.

see link - https://forums.ross-tech.com/index.php?threads/633/
....
2) Check the Measuring Value Blocks(MVBs) for the following (most MVBs will be labeled and you will be able to identify the data in the field):
  • Compressor shut off code
  • Refrigerant Pressure from the Sensor G65
  • Outside Temperature (filtered and unfiltered) (adjusted vs. not adjusted)
  • Evaporator Temperature
  • Vent Temperatures
For the problem in hand it may be that a different sensor (or just cleaning up the connectors on the existing sensor) may give a different reading as isn't it purely a resistance that is being translated into a temp value rather than having to tinker in the software?
 
Robin_Cox said:
I'm not a VCDS expert and am reasonably certain that what you've said is correct for the A2 as it is one of the earlier systems that VCDS can work with - however there is an indication in one of the VCDS forum technical posts that some VAG systems at least can give a reading for both actual *and* an adjusted external temperature value - which makes me wonder if the same is possible if you know exactly which adaptation channel to modify to fine-tune the reading (in the same way that I can adjust the fuel tank needle position or other similar parameters in the dashboard).

However - it is not made clear how one would go about effecting the adjustment.

see link - https://forums.ross-tech.com/index.php?threads/633/
....
2) Check the Measuring Value Blocks(MVBs) for the following (most MVBs will be labeled and you will be able to identify the data in the field):
  • Compressor shut off code
  • Refrigerant Pressure from the Sensor G65
  • Outside Temperature (filtered and unfiltered) (adjusted vs. not adjusted)
  • Evaporator Temperature
  • Vent Temperatures
For the problem in hand it may be that a different sensor (or just cleaning up the connectors on the existing sensor) may give a different reading as isn't it purely a resistance that is being translated into a temp value rather than having to tinker in the software?
Click to expand...
Yes, just a resistor.
Mac.
 
for what its worth, @CrispyEdd my outside temp was measuring a good 10* over following a thermostat swap.

everything looked ok, no leaks etc so i took the grill off, gave the outside temp probe a little wiggle and its now ok!

could be slight corrosion on the connectors maybe? despite it being well wrapped it is rather exposed to the elements out there in front of the rad.

drew
 
roc-a-rhol said:
for what its worth, @CrispyEdd my outside temp was measuring a good 10* over following a thermostat swap.

everything looked ok, no leaks etc so i took the grill off, gave the outside temp probe a little wiggle and its now ok!

could be slight corrosion on the connectors maybe? despite it being well wrapped it is rather exposed to the elements out there in front of the rad.

drew
Click to expand...
Ill have a butchers at weeekend! good tip, full of hope now :cool:
 
hey @CrispyEdd did you get any further with this?

iv swapped the external sensor and the issue persists - car is reading 28.5 at the moment 😖

i used a non genuine audi temp sensor when it needed changing so wondering if that's causing issues? it's fixed my gauge not getting to 90 but now the ambient temp is erratic at best

ta
drew
 
Hi Drew, I was staring at it yesterday through the grill, I havent yet replaced it though :) Still annoys me even though its just +2 deg c.
Im not sure the coolant temp sensor will be doing anything with the ambient sensor, as far as I know they are totally separate. The coolant temp sender down side of a tdi is 4 wired, 2 for guage 2 for ecu i believe. THeres a coolant temp after the radiator also. Tis odd

So yours reds like +10 deg over ambient? Even after swapping it out? SO I would say thats either wiring corrosion or the reading comes from something else also...

One for the bigger A2 brains...
 
CrispyEdd said:
Hi Drew, I was staring at it yesterday through the grill, I havent yet replaced it though :) Still annoys me even though its just +2 deg c.
Im not sure the coolant temp sensor will be doing anything with the ambient sensor, as far as I know they are totally separate. The coolant temp sender down side of a tdi is 4 wired, 2 for guage 2 for ecu i believe. THeres a coolant temp after the radiator also. Tis odd

So yours reds like +10 deg over ambient? Even after swapping it out? SO I would say thats either wiring corrosion or the reading comes from something else also...

One for the bigger A2 brains...
Click to expand...
The Ambient Temperature Sensor, (to give it the official title), is connected to the Climatronic, so the conversion from resistance to something digital, probably happens in there. There are quite a few old posts with similar, 2 - 3C offsets, but no fixes that I could find. Sensor replacement, from older posts, doesn't seem to fix it either. So it looks like the "problem" is in the Climatronic, so maybe a clean up of the blue, 32 pin connector, (+, pin 29), and the infamous headlight earth, is worth a try.
Edit: The + connection from the sensor itself runs through a white T17 pin connector in the left A pillar, on it's way to the Climatronic, according to the schematic. I had a windscreen leak, and that area got pretty damp, so worth a check in there too.
Mac.
 
Last edited:
PlasticMac said:
The Ambient Temperature Sensor, (to give it the official title), is connected to the Climatronic, so the conversion from resistance to something digital, probably happens in there. There are quite a few old posts with similar, 2 - 3C offsets, but no fixes that I could find. Sensor replacement, from older posts, doesn't seem to fix it either. So it looks like the "problem" is in the Climatronic, so maybe a clean up of the blue, 32 pin connector, (+, pin 29), and the infamous headlight earth, is worth a try.
Edit: The + connection from the sensor itself runs through a white T17 pin connector in the left A pillar, on it's way to the Climatronic, according to the schematic. I had a windscreen leak, and that area got pretty damp, so worth a check in there too.
Mac.
Click to expand...
insightful as ever, mac. thank you
 
Just a little update, given recent cold and the fact my webasto works I've been diddled out of a few warm journeys by my temp sensor.

I swapped the sensor over for another one off a donor car temporarily.

It made no difference, it still reads +2.0\2.5c over!! Exasperation.

The other car read the same as it did before so it must be the wiring connector on my car or something further towards the ecu.

I'll do resistance check on the connector and clean it up..

So annoying it can't be adjusted or calibrated! Today at 5deg c it reads 7.5 so webasto would have fired up. Instead inrun around with cold engine for 30 mins.

Any help much appreciated. I also have another sensor in the post from @Ami
 
  • Like
Reactions: Ami
Sensor & your other parts on their way Edd, its via the sensor that the webasto know when to switch on I believe
 
You could measure the resistance & put a resistor in parallel to make it fire the webasto , however on Tuesday your sensor should arrive, I will post all your parts tomorrow, hopefully should be there on Tuesday,
I must remember to sort your air con parts next week, been a very busy week. :)
 
You must log in or register to reply here.
Back
Top