Sensors Part # 41A4373A .
I had gone through 3 or so years where my garage door would work perfectly fine all summer right up until the weather turned cold. EVERY year I would spend an enormous amount of time adjusting these sensors in an attempt to align them "better". At the end of the day they simply would not work, which meant I would have to walk back into the house and hold the garage door button until the door closed completely.
This year I was determined to win this battle. No more ridiculous button pushing from the warm interior of my vehicle in hopes that the sensors would give in and just let the obnoxious door close. I had taken a little different approach this year and did my research. Here I come to find that this is a very common problem when dealing with these sensors and in most cases the cause is simply that the sensors are going bad and not because the became misaligned. So, I figured I would bite the bullet and purchase some new sensors.
From what I understand, if your current sensors have a green light on both the sending unit and receiving unit, then you would want to replace them with the same (41A4373A) part number I had listed above. If your sensors have a green light on one and amber/red light on the other, then you would want to purchase part # 41A5034. In either case, please do your research to make certain that these will work with your unit before purchasing.
In the end I was able to purchase my set of sensors from Amazon.com for approx. $22.00 shipped. The installation took about 5-10 minutes and only required some wire cutters and a pair of pliers. After the installation was complete, I found that the new sensors were extremely easy to line up and I also noticed the light on the receiver sensor was much brighter than I had ever noticed before with the old set. This gave me some faith that it was getting a good signal and would work without a hitch. I put my hand in front of the receiver sensor and confirmed that the light turned off to verify it was functioning properly in case the door encountered an obstruction. I then tested out the garage door with the button in the house to make sure it went down without me having to stir up any 4-letter words.
Finally, I tapped the garage door button in the house then ran into the garage and tossed a box under the door and voila, the door auto reversed as the design intended. If I would have know that some $20 dollar sensors and 10 minutes of my time is all it would have taken to get my door working properly in the winter months, I would have spent the money the first year I noticed the problem.
I hope this post gives you insight on how to fix this problem and maybe I can save you the frustration of having to jump out of your car while nearing the end of your driveway because your door is not operating correctly.
You live and you learn! ;)