Liftmaster 41C4398A RPM Sensor Assembly

Product Description

Liftmaster 41C4398A RPM sensor assembly [Read more]

Features

• 41C4398A RPM SENSOR

Top Reviews

Sent bad sensor, can't return even after seller verieid. No Returns.
by Enigma Networks (1 out of 5 stars)
February 13, 2017

Tried to confirm that it would work with my LW5000EV Chamberlain Liftmaster and I was told it does. It doesn't. Sensor has 5 prongs, the one I got is 4, doesn't fit. I cannot return it either. Save money and buy local or check ebay. I'm stuck with a sensor that I cannot use.
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Symptom: GDO Opens 12" Then Stops
by Amazon Customer (5 out of 5 stars)
December 27, 2018

Lift-Master Garage Door Opener Model 1255LM from 1994.

Symptom: GDO Opens About 12" Then Stops.

Checked safety sensor light, rails, wheels, chain, pulleys, trolley, and carefully pulled door up and down manually while unhooked from trolley. Everything checked out so I ordered this part, 41C4398A, RPM Sensor Replacement, as suggested online. The assembly that arrived looked like a genuine OEM part to me. There are two differences between my old one and the new one, and the changes look like product improvements.

My old RPM Sensor was attached with only two plastic retainer prongs, and the new one adds a retaining hook that clips onto the side of the metal plate. I think this keeps the Sensor from wiggling out of position due to vibrations.

My old RPM Sensor has an Interrupter Cup with a 1-1/2" diameter, and the new one has a 1-7/8" diameter. I think this makes it more visible to the Sensor and reduces the likelihood of it catching on the Sensor if either should move from vibration, and weather-related expansion or contraction.

The new Sensor assembly solved my problem and the door opens normally once again. Following the included instructions, I checked my Safety Reversal System by testing it with a 2x4 laid flat on the floor, centered under the garage door. It did not reverse so I had to increase the DOWN limit by turning the DOWN limit adjustment screw counterclockwise 1/4 turn. The door reversed on the 2x4 correctly, and subsequently, without the obstruction, the door stopped in the appropriate position.

I disconnected the power to my garage door opener before beginning this repair, and I try to always think safety first!
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Blonde Female Saves The Day
by Data Diva (5 out of 5 stars)
May 25, 2013

When our garage door went wacko, so did my husband. He figured the whole thing was shot and shouted that we were looking at a $300 replacement. I quickly realized that was a lot of shoe money. I climbed my blonde, 5'5" self up a ladder and saw the cutest lavender button on my opener, blinking. A quick Google search diagnosed the problem and I landed here. I was worried about little ole me being able to replace this doohickey, but it was easier than I thought. Like another person said, the hardest part was getting the screws out. It was hot in my garage and I started to sweat, and I don't like that. Anyway, the new part didn't work at first, causing Captain Caveman to wig out again. I finally figured out the the little thingamajig with the prongs on the back wasn't pushed in all the way. Now it worked!!! I bought myself a new pair of shoes a a reward for all the money I saved. Do not pay someone your hard earned shoe money to replace this part. Even I can do it, so can you.
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medium fix, with cautions
by N. Walkner (5 out of 5 stars)
May 2, 2017

it fixed the problem, but it probably wasn't the problem. i think the wires on the harness were loose. even after installing this part, it still did the 1 foot out and 1 foot back move. only after wiggling the wires did it travel a full cycle. also, make sure the motor/worm gear is pushed all the way back and secured tightly with the 2 allen screws on the collar. if not, it is likely the interrupter cup will jump out of alignment when the motor starts

edit: after replacing it twice, this wasn't the problem. i had to replace the mainboard. apparently, over time (mine was made in 1998), the solder degrades and things fail. in my case it was the rpm circuit. in some cases you can resolder, but in my case it didn't work
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Perfect, cheap fix!
by Jordan Kellner (5 out of 5 stars)
September 22, 2019

While trying to diagnose this problem I was having after replacing a bad sprocket morning on my Craftsman 1/2hp garage door opener, I had taken off my rpm sensor to find that one of the solder points broke. Since the original was 20 years old, I replaced it with this one here and the garage worked perfect afterwards. Perfect fix!
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Worked great after some mods
by David Sullivan (4 out of 5 stars)
March 8, 2014

I repaired my old Liftmaster opener but had the runs-for-a-few-seconds-then-reverses symptom that is an indication that the speed sensor wasn't working. So I ordered this assembly and put it in. Same problem. The end cap that goes on the motor shaft did not interrupt the sensor beam when the motor was running in one direction. That was probably my fault for leaving too much "slop" in the motor shaft - but I really couldn't get it any tighter.

My solution was to shave some of the plastic off the end cap so it would fit farther down the shaft. It only took about 1/16 of an inch to have the opener work reliably. In retrospect, I probably could have done the same thing to the old part, but I'm just happy everything is working again.
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Super simple
by wd8lee (5 out of 5 stars)
January 25, 2014

This was exactly what I needed as per the owner's manual troubleshoot information. Five flashes indicated that it was the sensor so for the cost of $11 which included shipping, I had virtually nothing to lose. The only thing that kept me from installing it as soon as I got it was the extreme cooled weather. Once the temperature got above 20 degrees, I decided to give it a try. It was soooo easy! The instructions were very easy to follow and the hardest part for me was the screws that hold the outer housing. I ended up dropping and losing one of them. If you're considering calling a repairman for this problem, don't. I am a woman who is not big (5'3") so no brute force was needed. You'll save yourself at least $100 if you do it yourself.
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Good replacement
by insightful (5 out of 5 stars)
September 30, 2018

Like others noted, I am confused if I needed this sensor. While this sensor was a like replacement and worked exactly as the original (including) replicating the same error), I used this as a confirmation that the issue was somewhere else. After fixing the somewhere else, the garage door started working normally.

I am giving it 5* as it worked as replacement perfectly.
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Buy two .. Keep one as a spare
by Prof100,Top Contributor: Woodworking (5 out of 5 stars)
September 10, 2015

This is the fourth one. First one lasted 8 years. The 2nd lasted three years. I had a spare so when the same failure mode occurred it took me a while to recollect the required repair. Same symptoms of door starts down, stops and reverses. It acts like the safety sensors are not working. Chamberlain troubleshooting makes no mention of this sensor being the cause. I had a spare new in a box stashed away. Locating it in the unit was a trial and error exercise. Remmbering its location escaped me after 3 years. It is located on the end closest to the garage door. Removing and replacing the screws and covers takes most of the time. Replacing the rpm sensor is simple. It is a press fit. Make sure the round plastic wheel is seated fully so it breaks the beam.
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I believe it fixed the issue.
by Ken B (5 out of 5 stars)
January 16, 2018

This was easy enough to install. I'm not sure if my other one failed. But, my sons and I did finally get the garage door working again and this was the only part we replaced (as well as about an hour worth of getting the up and down settings correct after I messed them up a bit while troubleshooting). I should have just bought one of these in the first place before messing with everything else. It was inexpensive enough.

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