Active leveling errors

1. Clean the nozzles

Material that is stuck to one or both of the nozzles can influence the readings. Although the nozzles are heated up before the procedure begins, if a blob of material is too big, it will not melt away completely and will add to the height of the print core.

Before restarting active leveling, heat up the print cores and clean the outside of the nozzles. You can find printer-specific instructions here: UltiMaker 3, S series, Factor 4.

2. Replace the print cores

If the active leveling problems appear consistently with a particular print core combination, the problem could be caused by one of the print cores. The expected offset between the two nozzle tips is 1.5 mm. If the nozzle of one of the print cores is worn down (for example, if the tip is flattened due to the use of abrasive materials), the measured offset will be either too big or too small.

Inspect the print cores closely. If any damage or wear and tear is observed, replace the print core.

1. Ensure that the build plate is placed correctly

For active leveling to work, it is important that the build plate is placed on the Z stage and in its correct position.

• Glass build plate: For printers with a glass build plate, the glass must be placed firmly in the metal clamps at the back of the Z stage and the front metal clamps must be closed. Ensure that the clamps at the back are not bent upward as this can cause problems (see this article for more information). Note that the printer is unable to recognize the presence of the glass build plate; never select Confirm removal or start a new print job without the glass plate installed.
• Flexible build plate: Printers with the flexible build plate have a build plate detection sensor, which is enabled by default. Ensure that the build plate is installed and the sensor is not turned off. The build plate must be correctly aligned with the pins on the Z stage, and there must be no objects between the magnetic base plate and the flexible build plate, so that the flexplate lies completely flat.

2. Clean the build plate

When a nozzle is pressed against the build plate during active leveling, this can leave behind some filament residue on the plate. This residue can cause inaccuracies in the readings if you go through the active leveling procedure again. Make sure there are no impurities on the surface of the build plate, especially in the back-right corner where the Z offset probe is done.

Note: A thin layer of glue correctly applied to the glass plate will not affect the readings during active leveling.

3. Manually level the build plate

For active leveling to work correctly, there should be some space (at least 0.5 mm) between the tip of the nozzle and the glass plate at the start of the procedure. If the nozzle is already touching the glass, the printer cannot perform the measurements correctly.

Note: This section does not apply to UltiMaker printers with a flexible build plate (S6, S7, S8, and Factor 4). The build plate has a fixed position and there is no manual leveling procedure. If the nozzle is already pressed against the build plate at the start of the procedure, the Z stage could be assembled incorrectly or there is a different problem. Please contact support.

After having followed the manual leveling procedure multiple times, the build plate springs can become too loose and the bed too high. Turn the three thumb wheels below the build plate counter-clockwise to tighten the screws. Reset the bed back to the factory position:

• For the UltiMaker 3 and S3, there should be a distance of approximately 14 mm between the bottom of the heated bed and the top of the aluminum base plate.
• For the UltiMaker S5 and S6 (Glass), the thumb wheels should be fully tightened. Then, loosen with 2 full turns clockwise.

1. Check the lift switch calibration

It is important that the print core switching functions well. If not, the active leveling procedure will detect the same height for both cores, which also 'exceeds realistic values' and could therefore cause this error message.

If the print head does not move to the switch bay correctly, perform a lift switch calibration to properly store the position. This only takes a few minutes. Our support pages have detailed instructions on how to perform this calibration:

• Factor 4
• S series printers
• UltiMaker 3

Note: If the print cores still do not switch correctly after performing the calibration, there could be a different problem. Check this article for more information and troubleshooting: Print cores not switching correctly

2. Check the capacitive sensor wires and connector

Note: This section applies to the UltiMaker 3, S3, and S5. Other S series printers use an inductive sensor with a flexible copper flatwire. Instead, check if this flatwire is still connected to the PCB at the back of the print head. On the Factor 4, check if the cable at the back is not damaged.

The capacitive sensor board which enables active leveling is located in the front fan bracket of the print head. This is connected with a red (sensor) and white (shield) wire. Check if both of these wires are still properly connected. If they have come loose or show signs of damage, the capacitive sensor wires must be reconnected or replaced. Contact support for further assistance.

See the following pictures for reference:

OK: Both wires are securely connected to the board and no damage is visible.	Not OK: One of the wires is broken and disconnected from the board.

Also check the connection of the wires to the print head PCB. This connector is visible at the back of the print head. The capacitive sensor wires are the second connector from the left, as seen from the back:

3. Check the front fan cable

Note: This section applies to the UltiMaker 3, S3, and S5. On other S series printers, the front fan is connected to the inductive sensor board on the inside of the fan bracket and is less susceptible to damage or cause interference. It also does not apply to Factor 4 because the print core cooling fan is at the back and the hardware is very different.

If one of the wires of the front fan has become damaged through wear and tear or improper placement, it could lead to electrostatic interference on the capacitive sensor board. This would result in incorrect readings during the active leveling process.

It is not easy to check the whole wires without disassembling part of the print head. Instead, try temporarily disconnecting the front fan before retrying active leveling. The front fan (black-white wires) is the third connector from the left, as seen from the back:

Tip: If it is not possible to easily disconnect the fan, you can remove the two screws on each side of the header bracket, to slightly lower the side fan bracket. After disconnecting the fan, realign the side fan bracket and secure it with the screws.

Start another print and observe the leveling process. If active leveling succeeds with the front fan disconnected, the fan is defective. When the wire's insulation is damaged, the core can come into contact with the metal fan bracket, which disrupts the leveling measurements. The front fan should be replaced; contact support or your local reseller for further assistance.

Caution: Only disconnect the fan for testing purposes; do not run prints with the front fan unplugged. Stop the print after the active leveling process is done. The front fan cools the print cores. Without it, the filament will swell in the print cores, causing extrusion failures. In severe cases, the swell may block print core removal. If this happens, you will need to disassemble the print head.

4. Check the fan bracket alignment

Note: This section does not apply to Factor 4; the hardware of the print head is very different from the UltiMaker 3 and S series.

Make sure that the fan bracket closes properly and the bottom of the print head is completely flat. If the fan bracket, which contains the capacitive or inductive sensor board, is at an angle to the build plate, the readings will not be accurate.

If it is tilting forward, something may be preventing the bracket from closing completely. This could be due to material on the print core's heater block, an incorrectly placed nozzle cover, or an incorrectly placed fan. When it's tilting backward, the metal of the fan bracket could be bent. In these cases, it is recommended to contact support for further assistance.

1. Stable position

Active leveling relies on precise measurements. Ensure the printer is on a stable and flat surface. Touching the printer or print head during the leveling process can interfere with the measurements and corrupt the results.

2. Electrical interferences

Ensure the printer is not affected by electrical interferences. These interferences could be caused by Wi-Fi, radio, light sources like neon, other machinery, and more. When in doubt, try moving the printer to another location and retry.