Both driver and passenger temperature set at 19.5. If only driver in car, those temperature settings will remain. However immediately upon passenger entry, the passenger temperature will change to 22. Furthermore, dependant upon car interior temperature at that time, the passenger seat heating may also come on.
This has all the hallmarks of the bug that appeared with iD8.5, which to my knowledge has never been fixed. However, I can read that the bug results in temperature being reset to 22 when no passenger present. I can also read the bug results in temperature being reset to 22 on the entry of a passenger. Thus see two conflicting descriptions according to how the question is written. Only the latter would describe the behaviour I am experiencing.
Can anyone shed any light on that bug, and provide any details? If the car does have a bug then its just a case of awaiting a fix, there being no point in further investigation!
Thanks

Note: car has Technology Plus Pack which includes 3-zone automatic air conditioning.

Does the passenger in question have a digital key, or is this some sort of seat sensor thing?

Morecambe wrote

Both driver and passenger temperature set at 19.5. If only driver in car, those temperature settings will remain. However immediately upon passenger entry, the passenger temperature will change to 22. Furthermore, dependant upon car interior temperature at that time, the passenger seat heating may also come on.
This has all the hallmarks of the bug that appeared with iD8.5, which to my knowledge has never been fixed. However, I can read that the bug results in temperature being reset to 22 when no passenger present. I can also read the bug results in temperature being reset to 22 on the entry of a passenger. Thus see two conflicting descriptions according to how the question is written. Only the latter would describe the behaviour I am experiencing.
Can anyone shed any light on that bug, and provide any details? If the car does have a bug then its just a case of awaiting a fix, there being no point in further investigation!
Thanks

Note: car has Technology Plus Pack which includes 3-zone automatic air conditioning.

Is your climate control sync setting on or off?

It just sounds like it is off and when you are alone the car uses your driver settings for both sides in front (my iX behaves the same) so like a quasinsynched mode but when a passenger is in, it goes to whatever settings they had last (again, this is normal behavior in my iX). Not sure exactly how the climate system is in the iX3 but the one in iDrive 8 can control seated/ventilated seats automatically if you use the auto climate, but in the iX3 it may just be that the last passenger had them on and it reverts to the last used settings and not activated as part of an advanced auto climate function.

Thanks for replies. The passenger is detected by a seat sensor. The last passenger temperature has never been anything but 19.5, thus therefore expect same at start of new journey.

As for the software bug, this is the sort of thing found, the bug apparently being evident in iD8.5 and later:

Passenger Entry Trigger: When the passenger door opens and the seat sensor detects a passenger, it often triggers the passenger climate zone to re-engage, which, due to the bug, resets it to 22°C

Never had problem with ID 8.0 and 8.5 in my x5's

Morecambe wrote

Thanks for replies. The passenger is detected by a seat sensor. The last passenger temperature has never been anything but 19.5, thus therefore expect same at start of new journey.

As for the software bug, this is the sort of thing found, the bug apparently being evident in iD8.5 and later:

Passenger Entry Trigger: When the passenger door opens and the seat sensor detects a passenger, it often triggers the passenger climate zone to re-engage, which, due to the bug, resets it to 22°C

it was sounding like the sync issue we have on all versions of the iX but that was the rear climate sync not sticking and defaulting to 22C on every single drive whether there was a rear passenger or not. This was fixed by the latest OTA iDrive update (started rolling out like last week or something) according to people who received it after a long time of BMW apparently telling people it was not a bug but working as intended.

ggalanis wrote

Morecambe wrote

Thanks for replies. The passenger is detected by a seat sensor. The last passenger temperature has never been anything but 19.5, thus therefore expect same at start of new journey.

As for the software bug, this is the sort of thing found, the bug apparently being evident in iD8.5 and later:

Passenger Entry Trigger: When the passenger door opens and the seat sensor detects a passenger, it often triggers the passenger climate zone to re-engage, which, due to the bug, resets it to 22°C

it was sounding like the sync issue we have on all versions of the iX but that was the rear climate sync not sticking and defaulting to 22C on every single drive whether there was a rear passenger or not. This was fixed by the latest OTA iDrive update (started rolling out like last week or something) according to people who received it after a long time of BMW apparently telling people it was not a bug but working as intended.

wouldn't you know that minutes after typing that message, my app prompts me to download the latest OTA update (03/2026.30) for my iX. LOL

Now see Sync is lost after being shut down for extended period.  However if Sync is re-toggled by driver on startup, the sync’ed temperature holds when a passenger enters, and resetting to the default 22 does not occur.
Furthermore, if before leaving the car, the passenger temperature is manually set, say to 20.5, the driver temperature being left at 19.5., then sometime later, on starting the car only with driver, both temperatures are seen to be 19.5. This fits with “ggalanis” recent excellent description where he refers to “quasi-synch” behaviour when no passenger present.
However when passenger enters, instead of reverting to last set temperature, ie 20.5, the temperature is reset to the default 22.

Thus I appear to have two anomalies. First, Sync mode is not maintained after a period of downtime, which after reading posts, was to be expected. Second, if not actually set to Sync mode at time of passenger entry, instead of reverting to last set temperature, the passenger temperature is being reset to default 22.
Now I have a better understanding of what is happening, I can live with it. Have had too many BMWs to be surprised at the odd quirky behaviour, especially those of late!