# Zero sub movement in SITL

**URL:** <https://discuss.bluerobotics.com/t/zero-sub-movement-in-sitl/21068>\
**Category:** ArduSub\
**Tags:** sitl\
**Created:** [July 24, 2025, 12:22am UTC](https://discuss.bluerobotics.com/t/zero-sub-movement-in-sitl/21068 "2025-07-24T00:22:10Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Tautala](https://avatars.discourse-cdn.com/v4/letter/t/8c91f0/32.png) [@Tautala](https://discuss.bluerobotics.com/u/Tautala)\
**Post date:** [July 24, 2025, 12:22am UTC](https://discuss.bluerobotics.com/t/zero-sub-movement-in-sitl/21068/1 "2025-07-24T00:22:10Z")

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When I run ArduSub in SITL, arm it and set to auto mode the sub does not move. Ground speed is zero. I put debug code in mode\_auto.cpp and I can see that ModeAuto::auto\_wp\_run is saying that forward\_out = 0.999556 but no movment.

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**Author:** ![tony-white](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/tony-white/32/18385_2.png) [@tony-white](https://discuss.bluerobotics.com/u/tony-white)\
**Post date:** [July 24, 2025, 5:29pm UTC](https://discuss.bluerobotics.com/t/zero-sub-movement-in-sitl/21068/2 "2025-07-24T17:29:08Z")

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Hi @Tautala -  
Did you upload a mission with waypoints to the vehicle? Does a connected GCS or the autopilot logs contain any error messages?

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**Author:** ![Tautala](https://avatars.discourse-cdn.com/v4/letter/t/8c91f0/32.png) [@Tautala](https://discuss.bluerobotics.com/u/Tautala)\
**Post date:** [October 15, 2025, 10:45pm UTC](https://discuss.bluerobotics.com/t/zero-sub-movement-in-sitl/21068/3 "2025-10-15T22:45:25Z")

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I don’t know what the problem was and what I did to fix it but it’s working fine now. It’s possible I had ArduSub running in SITL on my desktop while I also had it running on the Pi with the same ID.