Hi , my plastic keyfob on my 2004 XC90 was falling apart , bought a new one , swapped all the parts over , but now it won't start , help !!?

 

There is a "chip" in the key. The "chip" in the new key needs to be registered in the CEM. That generally (there are work arounds using other aftermarket software) requires a VIDA subscription and a software download to tell the CEM to accept the signal from the new key ( and allow the car to start)

 

I just bought a new FOB cover for my 2017 XC90. Decided to change the battery while I had the cover off. My FOB didn’t work at first but then realized the prongs that need to touch the edge of the battery had gotten pushed down instead of sticking up along the side of the battery opening. I read a post from someone else on this forum about this! I didn’t have to reprogram anything- it’s just a cover for the electronic part of the FOB. 😉

 

I just bought a new FOB cover for my 2017 XC90. Decided to change the battery while I had the cover off. My FOB didn’t work at first but then realized the prongs that need to touch the edge of the battery had gotten pushed down instead of sticking up along the side of the battery opening. I read a post from someone else on this forum about this! I didn’t have to reprogram anything- it’s just a cover for the electronic part of the FOB. 😉
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For a 2017 that is true. However the OP has a 2004 which is a different key and remote setup.