PreArm: Check mag field (xy diff:1xx>100) doesn't go away

I’m having a pretty bad issue with my drone. Whenever I take it out, usually it will arm and fly for one flight, no matter how long(5sec-5min). Then, when I land it will not arm again and will give the message:

[19:27:56.355] Critical: PreArm: Check mag field (xy diff:118>100)

The first number(in this instance 118) does vary a bit, the highest I’ve seen is 158. This issue just started, and I’m not sure why or what caused it. Nothing really changed with my build. My specs are:

  • 30a ESCs
  • 3s 5ah LiPo
  • Matek H743-Slim
  • Matek M10Q 5883

Attached are some photos of the setup. I’ve checked for motor/compass interference before, and noticed practically none. I’ve tried re-calibrating the compass so many times, but it either serves as a one-flight fix, or just doesn’t work at all.




Redo the compass calibration.

You can also increase ARMING_MAGTHRESH from 100 to 160

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Would changing the arming max impact performance? I’ve tried recalibration about 25 times with no luck.

Try using the magfit tool.

While you claim there is little interference, your real world results suggest perhaps another story.

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I received this message as well. was not sure how to get rid of it. I go back and fix it later but for now i can use the below:

“ARMING_MAGTHRESH from 100 to 160” Thanks!

Thank you very much for this idea. I’ve used MP’s magnetic interference testing and even at 100%(no props), it’s remained at less than 5% interference. This could, however, be environmental because I was flying off of a rooftop which had a few AC units one building down.

The magfit didn’t work. The drone flew the first arm, then refused to take off again. Here’s a compass graph of my last flight. Does it look like vibration is impacting the compass?

Also please note that vibration is a severe issue with this model. To my knowledge, however, this is doesn’t cause compass issues.

If you try calibrate your compass, compass vs motor interference calibration still had the same problem. The9/10 your compass position is too near interference source

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Yeah I agree. The compass is 6 inches from motor and 5 inches from ESC. I’ll buy a proper motor mount instead of using this plastic boba straw and a zip tie lol.

By any chance you are using matek compass and gnss? Those are incredibly prone to this error