A heater error on one of the print cores can occur when the print core fails to heat up. The printer is trying to heat up the print core, but the print core does not report an increase in temperature. The display will show which print core is affected. This refers to a problem with the thermal connection between the print core’s temperature sensor and heater.
The cause of this problem almost always lies in the print core itself and can be fixed by replacing the print core. If the printer displays a heater error in the same slot again, but with a different print core inserted, there may be a different problem.
If the problem still persists, please contact support by raising a support request above.