Just had car serviced and they told me that key fob batteries number 1 and 3 were low. How do they know ? I never get a low battery warning from the car. Should the car tell me ? 2019 vRS Challenge with Virtual cockpit. Thanks. 

The key fob only has one battery!

I have 3 keys. The battery is low in keys 1 and 3

Ah.

Surprised they needed all three keys to service the car.

You'll find there's numerous threads regarding fob batteries and their 'new' replacements. 

They didn’t have all 3 keys, only 1. I’m not asking about replacing the batteries I’m asking about low battery warning from the car and if it should tell me. 

There was probably an error code stating which are (or have been) low.

 

I would expect the car to warn you, maybe try using the other two keys and see if that shows a warning?

It does say in the manual it should warn you of low batteries, but the car could have stored the fault codes from before that were not cleared out.

It might be a software glitch, where it has not appeared on the screen if this is a new fault.

 

Manual states that the range should be around 30m (if the local "noise" is not too great)

When the range is under 3m, then you should replace.

1 hour ago, JP33 said:

They didn’t have all 3 keys, only 1. I’m not asking about replacing the batteries I’m asking about low battery warning from the car and if it should tell me. 

I'd be asking how they knew about the other keys which weren't with the car.

3 minutes ago, ords said:

I'd be asking how they knew about the other keys which weren't with the car.

The car will have all 3x keys stored, and when he would have used keys 1 & 3, during a low battery situation, the car would store that just those 2x ID's are having a low battery situation.

Fault codes are sotred for low battery per remote. But they usually report in the MFD as well. After you replace batteries it can take a day or two for it to stop reporting low battery and clearing the fault codes helps get rid of the historics....

 

E.g VCDS fault scan when I bought my car..

 

204290 - Remote key 1 
          B1479 18 [009] - Current Too Low
          Confirmed - Tested Since Memory Clear
             Freeze Frame:
                    Fault Status: 00000001
                    Fault Priority: 4
                    Fault Frequency: 1
                    Reset counter: 36
                    Mileage: 90237 km
                    Date: 2021.04.24
                    Time: 19:31:07

204546 - Remote key 2 
          B147A 18 [009] - Current Too Low
          Confirmed - Tested Since Memory Clear
             Freeze Frame:
                    Fault Status: 00000001
                    Fault Priority: 4
                    Fault Frequency: 1
                    Reset counter: 0
                    Mileage: 90237 km
                    Date: 2021.04.30
                    Time: 13:56:05

Edited 16 November, 20223 yr by TheClient

I had low battery come up a couple of days ago.

I learnt early on, that if you replace battery straight away, it clears itself.  If you leave it, you then have to rebind key.