This error refers to a problem with the Z limit switch, which is located at the bottom of the printer, under the build plate. The limit switch is used for homing the build plate and ensures that it won’t move down any further when it has reached the bottom of the Z axis.
When this error occurs, it means that the Z limit switch is not triggered properly. This can either be caused by a problem with the movement of the build plate or by a problem with the limit switch itself. This error can both mean that the limit switch stays activated when it should be released, or that the switch is not activated when it should be.
The following steps are advised to resolve an issue with the Z axis or limit switch.
Check for obstructions
Objects under the build plate, such as printed parts or tools, can prevent the build plate from lowering completely. This means the Z limit switch will not be activated at the end of a print or during maintenance actions, such as build plate leveling.
Make sure the bottom of the printer is cleared of all objects. Never store items inside an Ultimaker printer. Additionally, check for small pieces of filament around the Z switch. A piece of filament stuck in the limit switch can keep the switch activated, leading to an ER204 message.
Check the limit switch
Lift the build plate and manually activate the Z limit switch. You can use your finger or a screwdriver to press the switch. Listen closely; the switch should make a clicking noise when activated. If this is not the case, the switch mechanism could be defective. Submit a ticket or contact your local reseller for a replacement.
You can also check the switch's connection to the electronics.
Note: Always take ESD precautions when exposing the electronics at the bottom of the printer. Handling the electronics in an unsafe way can cause damage to the machine. Submit a support ticket or contact your local reseller if you cannot work ESD safely.
- Turn off the printer and disconnect the power cable
- Carefully place the printer on its side
- Remove the two small bolts that secure the bottom cover and place the cover aside
- Inspect the connections shown in the image below
The Z limit switch is secured right next to the Z motor and has a short white wire with a black shrink sleeve. Check if the cable is connected securely to the mainboard and reconnect it if necessary. Visually inspect the limit switch and the cable for signs of damage. Submit a ticket or contact your local reseller for a replacement if the switch looks defective.
Check the motor movement
Another possible cause for the Z switch error message is if the Z motor is not moving at all. After making sure that the limit switch is functional and not obstructed, try moving the build plate via the menu.
If there is no response from the Z motor, the ER204 message will be triggered after some time. This indicates a hardware problem with the Z motor or the motor drivers. Please submit a ticket to contact support for further assistance.