The EV3 Ultrasonic Sensor (45504) has been out of stock for a long time. Is the sensor discontinued due to an accuracy problem?

Is there an alternate version of "Gyro Boy" that works without the Ultrasonic Sensor and uses Infrared instead?


  • You don't need to use the ultrasonic sensor if you don't want to. You can build whatever you want.
    – MindS1
    Sep 2, 2018 at 19:16
  • @MindS1, I know that, but the program probably won't work and I have to modify it correct?
    – Allan Xu
    Sep 2, 2018 at 21:58
  • you're correct, you'll have to modify the program. It should be as simple as deleting the code that uses the IR sensor to respond to the remote, and adding whatever function you want using the ultrasonic sensor block.
    – MindS1
    Sep 4, 2018 at 12:36

1 Answer 1


Balanc3r is a good alternative for gyro-boy: http://robotsquare.com/2014/06/23/tutorial-building-balanc3r/

However, why do you conclude that the 45504 sensor is out of stock? In my region (Belgium) it can be ordered from the lego website and is listed as "Available", also it is contained in the core educational set (45544) which is certainly still available from various sources...

  • Thank you for help. 45504 sensor is out of stock in larger markets such as US for a long time. That ususally is an indication that the product is discontinued, since the distributor soes not bother with replenish stock.
    – Allan Xu
    Sep 3, 2018 at 17:27
  • I switched the region to S@H to US and it indeed says "temporarily" out of stock. I'm inclined to think that this is indeed temporarily as this is a popular item with FLL teams and other educational projects... Sep 4, 2018 at 12:21
  • Yes, I have been waiting for the part availability for a long time and no luck. The 3rd part sellers price is ~500% higher than the listed price on lego site. If you happen to know a good source please share, since I really like to to be able to work with this sensor.
    – Allan Xu
    Sep 4, 2018 at 15:26
  • 1
    Have you tried ordering from lego education ? To me it seems available there at regular price: education.lego.com/en-us/products/ev3-ultrasonic-sensor/45504 Sep 5, 2018 at 6:55
  • @AllanXu Have you looked on Bricklink? Used IR sensors go for as low as $13 USD. bricklink.com/v2/catalog/…{%22color%22:0,%22iconly%22:0}
    – MindS1
    Sep 5, 2018 at 14:35

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