1 MALFUNCTION means there is a stored malfunction, I don't believe TELEAID or NO PHONE causes a MALFUNCTION reading unless they are broken as opposed to disabled due to no subscription.

Yes, the dealer should easily be able to go into the cars data and find the culprit. I've gone to the dealer with a 1 MALFUNCTION and they told me they couldn't retrieve the fault, but a tech on this forum said this wasn't so and they can find the issue under these circumstances.

Check your owners manual because I think when your 1 MALFUNCTION shows ( as opposed to being stored, not certain ) you can flip through the menu with the thumb control buttons and find the fault explained.