# BLTouch does not compensate for bed level correctly

• Printer: Anycubic Mega S.
• Mods: BLTouch, Dual material with G-code-powered switch.
• Firmware: Marlin 2.0

A couple of weeks ago I had a print failure when printing PETG. Now whenever I use auto bed leveling, it doesn't compensate correctly. The nozzles will be too high on the left side of the bed, and too low toward the right. I checked my firmware configuration, and everything appears to be OK. I also suspect that the failed print may have knocked the Z endstops out of alignment.

I recalibrated the Z-offset on the BLTouch and ran a probe repeatability test. Everything came out fine. My Configuration.h can be found here. As well as a picture of the hotend setup below.

Edit: I tried leveling the bed manually before using ABL. Still had the same problem.

Edit 2: I looked more closely at the bed leveling logs and noticed that it is reading the bed level incorrectly, contrary to my previous tests. I do not know what this means, but I suspect it has to do with misaligned endstops. Could this be correct?

• Are your nozzles perfectly level? What you're describing sounds like they aren't. Mar 21, 2021 at 16:38
• @Rykara, you are correct, the nozzles were misaligned. I releveled them, but the original problem still lingers. Mar 22, 2021 at 16:13
• You think one Z axis might be slightly higher than the other? Have you aligned them to the same height like in this video? Apr 2, 2021 at 21:34
• Alright, I tried re-aligning the Z axis a couple times. It didn’t solve the problem. However, the distance from the bed to the nozzle at each side changed slightly (w/ auto leveling active). Apr 10, 2021 at 21:31