Outside air temperature update

Had a similar problem with my Temperature sensor. It was was the earth loose behind front passenger side interior trim panel
 
The panel to left below the glovebox Panel that joins to the interior sill top cover.Below the the A pillar
 
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terrywindy1 said:
The panel to left below the glovebox Panel that joins to the interior sill top cover.Below the the A pillar
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The thermistor, that senses the temperature, will be around 20 years old, so has probably drifted a bit. Also, because it is a resistor, any dogy joint between it, and the DIS will introduce additional resistance, and error. From the dash, I suspect it goes via canbus to wherever it's needed, but it's digitised in the dash, so no errors from there on.
The earth is the one behind the headlight, so check it out too.
Mac.
 
Thank guys, odd that it didn't change when swapping sensorswhich must be wires and earth. I removed and cleaned all earth's when I did engine swap. Starts in a millisecond
 
It is quite exposed isn't it, so the internal connection, thermistor, (resistor), to wire is likely to be a bit suspect.
If we could get a few resistance reading, from a sensor at a few different temperatures, (-10, +10, +20 +30), we could match it to a commercially available thermistor.
Mac.
 
PlasticMac said:
It is quite exposed isn't it, so the internal connection, thermistor, (resistor), to wire is likely to be a bit suspect.
If we could get a few resistance reading, from a sensor at a few different temperatures, (-10, +10, +20 +30), we could match it to a commercially available thermistor.
Mac.
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I have Just posted one to Edd, I have a few more, will check the resistance on them Mac, very rare for a them to go wrong though.
 
Not just a thermistor. The system also uses an algorithm. This works to damp the sensor readings so cold gusts of wind does not have the reading constantly changing. This is similar to the rest of the Audi range.
 
Im leaning towards the actual plug socket and corrosion in there then, given my earths are good the visible wiring loom is good and I've swapped sensors to no avail, can only be the plug socket or issue with wire/pin corroding? something so small and simple causing me grief as i hate missing out on the sebastopol when its say 4-5 deg as it reads 7/8 deg!! nothing simple with the A2 eh?! Little blighters.
 
If it were me I would replace the wiring loom to the OAT sensor as far up into the engine bay as possible. Plug and socket could well be corroded but the wiring loom may also have black wire corrosion.

Out of interest this false temperature reading is experienced throughout other Audi models, just unfortunate it is the trigger for the Webasto and no I would not recommend bypassing it.
 
update for anyone with the same issue as me and @CrispyEdd - i added a new earth strap which has resolved the issue.

the earth was added here which makes it very accessible

Screenshot_20240303-112832.png

drew
 
This is great news! I'll give it a go later!! I've soldered a whole new connector on and swapped sender. And then forgot to check it, been up on ramps since!! I'm out there today so will take a peeek
 
I don't have webasto now on my ATL but was thinking about some kind of switchable timed bypass (say 30 minutes fudged 5deg given to controller) so electric element is up and running in the morning when its 6,7, maybe 8 deg. In general..what are you comparing outside temp display to? Phone app? other car?
 
robskiA2tdi said:
I don't have webasto now on my ATL but was thinking about some kind of switchable timed bypass (say 30 minutes fudged 5deg given to controller) so electric element is up and running in the morning when its 6,7, maybe 8 deg. In general..what are you comparing outside temp display to? Phone app? other car?
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You'd have to power the heater from the mains, the battery alone, without the engine running, can't provide the power.
Mac
 
Just to close thisone out I have soldered on a complete replacement sender and plug unit and this has solved my temp woes so likely a corrosion issue at the crimped end and plug of the original...happy days :)
Think i will add and earth aswell just for good measure!
 
CrispyEdd said:
Just to close thisone out I have soldered on a complete replacement sender and plug unit and this has solved my temp woes so likely a corrosion issue at the crimped end and plug of the original...happy days :)
Think i will add and earth aswell just for good measure!
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Have kept a sensor on my desk for you as & when you need one.
 
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