ERROR - STOPPED Temp sensor bed, A visual Ultimaker troubleshooting

The firmware has detected that the temperature sensor of the bed is reporting incorrect values. Without proper feedback from the sensor the firmware can't control the bed heat so to protect the printer and for safety reasons the firmware will prevent you from using the printer until this problem is fixed.

Important warranty note: before you perform any of these steps you must contact the Ultimaker support team first

Most likely the error is caused by a connection issue. This can happen in a few locations:

Where the wires connect to the PCB underneath the printer

At the bed connector

The wires themselves may be damaged

The easiest thing to check is the connector on the heated bed so let's start there. Follow the cables that connect to the bed. There will be four wires two thick ones and two thinner ones. The sensor wires are the thinner ones. Try tugging gently on these wires and make sure that they are securely fastened. If they are not properly secured you will need to remove the heated bed so that you can access the connector and re-seat the wires properly.

If any of the wires are loose you will need to remove the heated bed so that you can reach the connector. Start by removing the strain relief that hold the wires to the bed. The bed is held in place by three screws that connect to the three thumbscrews on the underside of the build plate. Unscrew all three screws completely and lift the bed off. Be ready to catch the thumbscrews as they are not held in place. You will now have full access to the bed connector and it should be straight forward to re-insert the wires and tighten them into place. While you have access you should also inspect the solder joints that hold the connector to the heated bed. Check for cracks or other damage. If you find a bad connection you will need to re-flow the solder joints. If you are not comfortable doing this yourself then maybe you know someone who has experience with a soldering iron. If not, get in contact with us and we'll make sure to get it fixed for you.

Now check that the sensor is properly plugged into the PCB at the bottom of your printer. To access the PCB you will need to remove the protective metal cover. There are two metal covers, the one you want to remove is the bigger one. The cover is held in place by a couple of screws that you unscrew from inside the print area of the printer. Start by lifting the bed out of the way by grabbing the bed with both hands as close to the back of the printer as possible and lifting it straight up. Lay the machine on its side and remove the two screws and finally remove the cover, it might take a bit of wiggling back and forth to dislodge the cover. The sensor cable is white and brown and should be connected to "Temp3" on the PCB:

Unscrew these two screws to release the electronics cover.

Check that the white and brown cable is inserted into "Temp3".