# C450A4 - Force-Torque sensor is expected - but cannot be detected **URL:** \ **Category:** Technical Questions\ **Created:** [June 19, 2021, 6:23pm UTC](https://forum.universal-robots.com/t/c450a4-force-torque-sensor-is-expected-but-cannot-be-detected/15006 "2021-06-19T18:23:10Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![mike](https://avatars.discourse-cdn.com/v4/letter/m/58f4c7/32.png) [@mike](https://forum.universal-robots.com/u/mike)\ **Post date:** [June 19, 2021, 6:23pm UTC](https://forum.universal-robots.com/t/c450a4-force-torque-sensor-is-expected-but-cannot-be-detected/15006/1 "2021-06-19T18:23:10Z")
We had a relatively new UR5E have this problem earlier this week. We swapped it at the customer with one of our spares and it worked fine for a few days. The customer called and said the problem happened again, and also happened on another robot in the same cell. No changes that I know of, both robots were running Polyscope 5.9 before the error. We upgraded both to 5.11 as part of troubleshooting with no impact. Has anyone seen this type of problem before? I’m heading to the plant to swap sensors again, but as it’s happening on 2 different robots, makes me think it’s not a hardware failure. Here is the application: [Arnold Gauge Hole Poker Check - YouTube](https://www.youtube.com/watch?v=0PhGCsveb5Y) ---
**Author:** ![pho](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.universal-robots.com/pho/32/2275_2.png) [@pho](https://forum.universal-robots.com/u/pho)\ **Post date:** [June 25, 2021, 6:12pm UTC](https://forum.universal-robots.com/t/c450a4-force-torque-sensor-is-expected-but-cannot-be-detected/15006/2 "2021-06-25T18:12:16Z")
This error can be the result of installing a tool with screws that are too long. They push on the sensor and damage it. ---
**Author:** ![mike](https://avatars.discourse-cdn.com/v4/letter/m/58f4c7/32.png) [@mike](https://forum.universal-robots.com/u/mike)\ **Post date:** [June 25, 2021, 6:28pm UTC](https://forum.universal-robots.com/t/c450a4-force-torque-sensor-is-expected-but-cannot-be-detected/15006/3 "2021-06-25T18:28:29Z")
Hi Pho, thanks! That was one of the first things we checked. The screws were supplied with Robotiq Hand-E grippers and appear to be correct. We are working through a gripper swap to see if that makes any difference. ---
**Author:** ![terryc](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.universal-robots.com/terryc/32/3006_2.png) [@terryc](https://forum.universal-robots.com/u/terryc)\ **Post date:** [June 30, 2021, 2:45am UTC](https://forum.universal-robots.com/t/c450a4-force-torque-sensor-is-expected-but-cannot-be-detected/15006/4 "2021-06-30T02:45:19Z")
Just had this one come up now. Had a thin protective cover on the arm and apparently it was “twisted up” as reported by maintenance. Will try to include a photo when I get one. ---
**Author:** ![randy.campbell](https://avatars.discourse-cdn.com/v4/letter/r/97f17d/32.png) [@randy.campbell](https://forum.universal-robots.com/u/randy.campbell)\ **Post date:** [October 4, 2021, 1:38pm UTC](https://forum.universal-robots.com/t/c450a4-force-torque-sensor-is-expected-but-cannot-be-detected/15006/5 "2021-10-04T13:38:54Z")
Just heard of this fault coming up on a system of ours that has been in place and running for about 9 months without issue. Any more information available as to what else we could/should look for? ---
**Author:** ![mike](https://avatars.discourse-cdn.com/v4/letter/m/58f4c7/32.png) [@mike](https://forum.universal-robots.com/u/mike)\ **Post date:** [October 4, 2021, 2:42pm UTC](https://forum.universal-robots.com/t/c450a4-force-torque-sensor-is-expected-but-cannot-be-detected/15006/6 "2021-10-04T14:42:40Z")
Especially if under warranty, I’d just swap-out the FT/sensor. The robots we had with the issue were all purchased just about a year ago. ---
**Author:** ![randy.campbell](https://avatars.discourse-cdn.com/v4/letter/r/97f17d/32.png) [@randy.campbell](https://forum.universal-robots.com/u/randy.campbell)\ **Post date:** [October 4, 2021, 3:06pm UTC](https://forum.universal-robots.com/t/c450a4-force-torque-sensor-is-expected-but-cannot-be-detected/15006/7 "2021-10-04T15:06:58Z")
Thanks for the feedback mike. That fits our timeline as well. ---
**Author:** ![anon74189313](https://avatars.discourse-cdn.com/v4/letter/a/6bbea6/32.png) [@anon74189313](https://forum.universal-robots.com/u/anon74189313)\ **Post date:** [February 2, 2022, 4:51pm UTC](https://forum.universal-robots.com/t/c450a4-force-torque-sensor-is-expected-but-cannot-be-detected/15006/8 "2022-02-02T16:51:50Z")
I am facing the same problem. The weird thing is, we use this robot in a research setting and there was no tool attached to it. It was literally working a couple of minutes ago. Did anyone find a quick fix? ---
**Author:** ![mike](https://avatars.discourse-cdn.com/v4/letter/m/58f4c7/32.png) [@mike](https://forum.universal-robots.com/u/mike)\ **Post date:** [February 2, 2022, 5:08pm UTC](https://forum.universal-robots.com/t/c450a4-force-torque-sensor-is-expected-but-cannot-be-detected/15006/9 "2022-02-02T17:08:33Z")
I worked with UR support, they sent a new Force Torque sensor. There was no software fix that worked. And, the error occurred with or without the gripper. A reboot would sometimes let it run a few minutes, but replacing the sensor solved the problem. ---
**Author:** ![bba](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.universal-robots.com/bba/32/555_2.png) [@bba](https://forum.universal-robots.com/u/bba)\ **Post date:** [February 3, 2022, 2:51pm UTC](https://forum.universal-robots.com/t/c450a4-force-torque-sensor-is-expected-but-cannot-be-detected/15006/10 "2022-02-03T14:51:17Z")
If upgrading to polyscope 5.11.5 does not resolve the C450 error then the force torque sensor assembly will have to be replaced. There is no other way around this. 5.11.5 or newer SHOULD resolve it in most cases.