Audi a4 b9 key fob not working after battery change

Check the new battery isn't dead, I'm fed up buying batteries only to find they are dead. I bring a small battery tester now when buying any and test them in the shop in front of the cashier.

Have you tested if the "new" battery isn't dead? A lot of those batteries are years old before they get sold and are either half dead or dead.

I tried 3 different "new" batteries from different shops last week, all were dead. They were cheap branded ones though. It's worth checking them as an easy way to know before going for the next options others can advise hopefully if it's a known issue.

Did you put the battery correctly to the key. It's easy to make mistakes with negative and positive sides.

I had 3 differently sourced 6 packs of Duracell batteries with expiry dates after 2030 and not a single one worked in the car remote when I changed after a low battery warning. Went to the chemist and got one it worked first go, was even same brand. I'm not sure if they store bad or what, I had mine at room temperature and out of sunlight so should have been grand.