E300-18

One of the garage door buttons on my rearview mirror periodically quits working. When this happens, I go through the process again to program it. It will work for another few weeks or months, and then it does the same thing again.

I bought the car new at the end of 2017, and I've always used the left button for my garage door and the right button for a gate at the end of our driveway. The issue started when had a new gate installed about 1.5 years ago. The garage door always works fine, but the gate has issues. The underlying problem could be in the gate, but my wife's Subaru doesn't have any issues.

I also tried programming the middle button for the gate, instead of the right button. That button never works. In addition to programming the button, I need to program the gate to learn the new remote, and the gate never learns it.

It seems like the gate and the car both have some justification to claim that it's the other one's fault. Any thoughts?

W205C43PFL

Might have to do with interference or the amount of devices in memory, see if this is similar to the problem you are facing: https://mbworld.org/forums/glc-class...door-code.html

superswiss

Yes, it sounds like you have not completed the programming for your gate and the rolling code hasn't been synchronized, so eventually it stops working. Garage door and Gate openers as mentioned above can only hold a fixed number of remotes and once they reach the limit, you can't program any more. I know you said you replaced your gate, but it's not clear from that if you got a new virgin gate opener as part of that. There's a way to reset garage/gate openers and clear all the codes from it. Unfortunately, you'll have to reprogram all the remotes after that, but at least you know the memory is clear and only the remotes you program fresh will be part of it.

streborx

Is your gate opener a rolling code or fixed code type?

E300-18

Thanks for the link. That thread was the exact same issue that I'm seeing. It's even the same brand of opener that's involved, List Master. In that thread, the OP eventually concluded that the Homelink module in the car is bad. My car is out of warranty, and it wouldn't be worth it to me to pay a significant amount of money to fix it. If I need to, I'll buy another remote to store in my car.

The gate opener came with four remotes, and we programmed the rearview mirror buttons in two cars. The only thing giving me any problems is the Mercedes.

E300-18

The new gate was a completely new system, with a new opener. My old gate was a simple farm gate, with a Mighty Mule opener attached. The new gate is professionally installed with a Lift Master opener.

The programming for the old gate opener was simpler. I just followed the process to program the car button, and everything worked. The new gate is like my garage door opener. It's a two-step process. I first configure the car button. Then I open up the gate opener to push the "Learn" button, to get it to recognize a new remote. Is that the same as synchronizing a rolling code? I don't recall seeing that terminology in the instructions.

The other thread mentioned clearing the gate opener memory and restarting everything from scratch. In that case, he still had the same issue a few weeks later. Two of our remotes are with family members, so I'm reluctant to attempt that path.

superswiss

Correct, the steps after pressing the LEARN button is what synchronizes the rolling code. I thought this part doesn't succeed when you did it with your gate or did I read that wrong? If it doesn't succeed, then this would be the source of the issue.