actbadtothis

So I got a 2008 550i almost a year ago and after spending the last 11 months catching up on the maintenance and services the past owners neglected I've finally be able to getting around to doing some more ( non-essential to drive) fixes / mods which has brought me here

I got this 550i (comfort access) and at the dealership they had unlocked and locked it with the keyfob I have, I had even done it that day as well. The next morning i wake up and go to the car to head to work and the doors wont unlock, no buttons on the keyfob are working, First thought was the battery so I got a new one in and it worked one time then stopped so i just opened they doors with the hard key and put the fob in the ignition to drive and have done that untill recently.
After some frustration of the fob not working i did what any dumbo would do and hit the fob up against a metal pole and for the next 30 minutes everything on the fob worked, opening the doors key-less start, the whole thing. got gas and it stopped working again.
looking up some common locking issues i noticed a lot of people talk about the diversity amp in the back getting water damaged and of course my car and its crappy past owners let the back window seal degrade to a chunky plastic and 90 % of it was missing so I went to work to open up the amp and see if i saw any signs of water damage. I did not but still scrubbed everything with a wire brush and put it back together. No luck

So recap
Checked fuses [good]
Checked diversity amp [good from sight inspection]
keyfob has had battery replaced
keyfob worked one other time after hitting it against a pole

I really want to think its not the fob just for the simple fact that they are way to much money to be replaced. Any thoughts or suggestions to check before i blow almost a full week of pay on a new key? i want to replace the fob only if im 100% sure its the problem but i just feel like the fact it was working until the night i got the car is just not right but maybe i have the worlds worst luck haha.

donpb

I wouldn't have thought the key fob was at fault until you banged it up against a metal pole. It could still be the diversity amp. With mine, my key won't work unless I'm near the diversity amp. Prior to that,I used to could be over a hundred feet away and still lock/unlock my car. Maybe just get an indy mechanic to diagnose it for you.

seanjordan20

Just go to battery plus or advance auto. I think they still have the key signal stand for key fobs at the counter. Press the buttons in front of it and that will tell you if the fob is actually working. Then go from there.