E90 M3 Comfort Access/Key issue

[Fastalpine]

Hey all:

I have a 2011 M3 sedan optioned with Comfort Access.

Recently I started getting a key error when I would start my M3. Key is always kept in my arm rest console.

I figured the battery was going bad in the fob so I replaced the 2032 battery with a brand new one. I have done this in the past many times to fix a comfort access key issue.

This time around there was no change in the key fob. The car still says no key found until I put the key in the slot.

I then tried to use the key to unlock and lock the car with the buttons and the door handle and nothing works.

I figured maybe the key fob was completely dead so I tried my spare key and that key also acts the same way as my main key.

It is almost as if the car's comfort access system has failed. Does anyone know a fix for this issue?

I scanned the car with a nice scanner and ran the CA module and it found no errors. I also checked fuses for the locking system and found no blown fuses.

I am stumped at this point as to what to look at next. Any help would be appreciated.

[Soden82]

Maybe it’s a battery or IBS issue? My CA doesn’t want to work sometimes because I don’t drive the car much and my battery is old.

[Helmsman]

I'd check up on the antenna. There are a few interesting threads, heres one from quick search:
https://www.m3post.com/forums/showthread.php?t=2006151

https://www.m3post.com/forums/showthread.php?t=1895704

[BP709]

You need to use ISTA or something where you can view status requests and perform the test modules. That way you can view if the vehicle is seeing the buttons pressed, hand at door handles or key in the interior. You’ll just be playing a guessing game otherwise. Too many components of the system CA module, multiple antennas, antenna amplifier, etc.

[Fastalpine]

Originally Posted by Soden82

Maybe it’s a battery or IBS issue? My CA doesn’t want to work sometimes because I don’t drive the car much and my battery is old.

Battery is good and almost always on a tender when not driven.

What is weird is it just stopped working out of the blue. One day it worked fine and the next nothing. It never had an issue with the door handle response and I could lock and unlock with the fob from a pretty far distance too.

BP709 That is a good idea. I will have to go somewhere to have that looked into.

[Ximian]

Originally Posted by Fastalpine

What is weird is it just stopped working out of the blue. One day it worked fine and the next nothing.

That's generally how things break.

My driver's door handle is also giving me a code (A097) and doesn't do keyless locking or unlocking. Passenger side door still works.

Considering your comfort access failure is worse and the "nice scanner" didn't pick up any codes, I suggest getting something good like Bimmerlink to read the codes.

OBDLink CX adapter and Bimmerlink is probably the cheapest and easiest way to reliability read the codes.

[Fastalpine]

Originally Posted by Ximian

That's generally how things break.

My driver's door handle is also giving me a code (A097) and doesn't do keyless locking or unlocking. Passenger side door still works.

Considering your comfort access failure is worse and the "nice scanner" didn't pick up any codes, I suggest getting something good like Bimmerlink to read the codes.

OBDLink CX adapter and Bimmerlink is probably the cheapest and easiest way to reliability read the codes.

Thanks for your sarcastic reply. It is much helpful.

[panda-R]

Originally Posted by Fastalpine

Thanks for your sarcastic reply. It is much helpful.

That was a sarcastic reply?

[Helmsman]

Originally Posted by Fastalpine

Thanks for your sarcastic reply. It is much helpful.

Huh...?

[Fastalpine]

Originally Posted by Ximian

That's generally how things break.

My driver's door handle is also giving me a code (A097) and doesn't do keyless locking or unlocking. Passenger side door still works.

Considering your comfort access failure is worse and the "nice scanner" didn't pick up any codes, I suggest getting something good like Bimmerlink to read the codes.

OBDLink CX adapter and Bimmerlink is probably the cheapest and easiest way to reliability read the codes.

I had the codes read with a BMW tool and there was 0 codes found. Nothing about the door handles or module being bad. Even looks like all the antennas are ok too.

I disconnected the battery overnight and reconnected in the morning with no change.

I think my next step is to make sure both my key remotes are transmitting properly. Not sure where else to go from here.

[Helmsman]

Originally Posted by Fastalpine

I had the codes read with a BMW tool and there was 0 codes found. Nothing about the door handles or module being bad. Even looks like all the antennas are ok too.

I disconnected the battery overnight and reconnected in the morning with no change.

I think my next step is to make sure both my key remotes are transmitting properly. Not sure where else to go from here.

Good luck.

[Ximian]

Originally Posted by Fastalpine

I had the codes read with a BMW tool and there was 0 codes found.

Which code reader? Not a single code for anything seems unlikely.

Have you had the car battery load tested? I've had a failed one that showed good voltage but would have issues like the car alarm randomly going off.

[Fastalpine]

Originally Posted by Ximian

Which code reader? Not a single code for anything seems unlikely.

Have you had the car battery load tested? I've had a failed one that showed good voltage but would have issues like the car alarm randomly going off.

INPA and had someone remote in and go through the modules including looking at both door handles.

I am also thinking battery as well at this point. I have had the car for 4 years and within the last 2 years haven't been driving it as much and putting it on and off the trickle charger.

This morning I got a battery discharge error. I currently have it hooked up to the tender and will see what happens.

[Ximian]

That video has good diagnostic information using ISTA. Get a KDCAN cable from someplace like Bimmergeeks and you can find ISTA around as well.

In the mean time, check the module in the trunk and all the antenna wiring. Perhaps you'll get lucky that the module was just slightly unplugged and all it takes is reinserting the harness.

[panda-R]

It's nice to see you two getting along! 😁