I have an Anet A8 with Marlin Firmware 1.1.9 and I installed a BLTouch sensor. When I start the system the BLTouch does its self test (extend and retract the probe twice) and then lights up red. When I "Auto Home", it homes X, then Y and then extends and retracts the probe and moves up a few millimeters. Then with the probe retracted it moves down until the nozzle crashes into the table. The same happens when I select "Level bed".

Safe Homing is active.

What am I doing wrong?

My current Configuration.h can be found here.


You must invert the logic of the endstop Z_min.




  • $\begingroup$ @lukaspanic If your table is colliding with the nozzle, you must invert the Z motor cables $\endgroup$ Feb 3 '19 at 5:22
  • $\begingroup$ Nope, that didn't change anything. It's still doing the exact same thing. If the BLTouch would be extended it would probably be fine but it doesn't seem to know it's supposed to do anything. $\endgroup$
    – lukaspanic
    Feb 3 '19 at 23:45

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