key fob kaput
 

Hello all, not tried the 'spare' but key that I have had since got car gave up ghost....managed to lock it but it did not unlock with key fob...had to manulaly unlock then manually lock....stuck key in fridge and after 10mins tried again and key works..so battery? how feasible is it to replace the battery? tad worried about taking knife to it as did this on wifes e46 key and destroyed it a while back....plus what battery is needed?any ideas much appreciated

Not just the battery but the switches and solder joints fail.

Best upgrade I did in the six years I had my e53 was getting a factory replacement key! Bite the bullet and get a real key. You can use the original as an emergency spare.

ta for quick reply....I got a spare but need to try it...and if all ok...then thinking of attacking the flat one

There are videos on how to replace the soldered in battery. I did with both my original keys as well as reflow the bad solder joints. I got working keys out of the process but they didn't work great and after a couple years didn't at all. The weak signal made it seem like the car receiving antenna was failing but when I finally got a new factory key out worked from as block away.

If you have one solid working key by all means look into cutting the non working one open to replace the battery if you have decent soldering equipment and skill.

My plan was to refurbish my failed key once again after I bought a factory key. Car was took out by a deer never got the chance.

Hmmm... my factory new key doesn't work that far away. I gotta get about 25 feet from it before it'll beep.

For me the FZV antenna failed intermittently at first, and then finally stopped working. To my knowledge there is no way to distinguish between a failed battery and a failed FZV. Even using the PA Soft scanner it couldn't tell that the FZV was bad, it just didn't register the key press signal and couldn't reinitialize the keys. (If you can't initialize a brand new key you would know that the FZV would be bad, albeit after you've already spent the money on a new key.)



There's a guy that rebuilds diamond keys as well, though I wouldn't argue with just biting the bullet and buying a new one.



Just another one of the fun and exciting ways these cars break. Fun and exciting for people who like to fix them, not so much for people who just like their cars to work.

If you can find my write up on key I show how to measure the voltage using a couple pins though the rubber button.

I’ll look for pictures but you can confirm voltage before and during button press

I replaced the battery in my non-working fob. It was pretty easy. Works now.

dunno what happened but today is working and even from a reasonable distance and have the spare too just as old that works too....i think i can find a place to clone working key in meantime and also order the vl2020 after opening 'old' key to see which pins it has

Yup indeed no time to be dabbling alas....