Hi, I'm new here so apologies if I am not following protocol re: posting a new thread, hope this is ok.

I just bought a used 2003 M45 yesterday, got it home and everything seems fine (except the service engine light came on & the guy said it was because they replaced a tire & some rotors for me, but I'd need to see a dealer to reset the computer or something).

Now when I try to start it, I don't have any luck.

Basically if I don't use the transponder/remote thing over the key and insert the key directly into the ignition, it turns the whole way & the starter engine will turn, but the transponder is required to actually start the car so I can't go anywhere. Even after reprogramming & checking that the remote functionality works (locks/unlocks car), when I put the transponder into the ignition it doesn't allow me to turn the key.

The car's in park, I tried depressing the brake and emergency break, locking the doors, putting my ez pass in the trunk (in case it was interfering). No luck - any ideas? I replaced the battery in the transponder/remote so that's one possible reason it's not working. Another is I had my ez pass in my pocket and perhaps that did something to screw it up?

Please help!! Thanks

have you tried calling roadside assistance? about a week after I got my car I was filling it up w/ gas and when I went to start it, they key wouldn't turn. All I had to do was turn the steering wheel left and right while trying to turn the key and it worked perfectly. I'd try that and if it doesn't work called roadside and they'll take care of you.

ok check this...get in...stick the actual transponder in the ignition like you are gonna start it.... does the security light come on and stay solid??

Yeah it was doing that. Anyway it looks like we found the problem. I went to Radio Shack to replace the battery and the kid dropped the open remote on the floor. I guess the chip is not attached to the rest of the unit and fell out during the process. So, I was using a chipless transponder. Long story short I believe I recovered the chip (we found a small plastic thing in the store), but I won't know until Monday if it works, since the dealership's closed. This could potentially be very expensive but at least I figured out the problem. Thanks for the help guys!