Check your firmware version. Here are some notes about "heater error":
heater error
You get an error if the heater can't move a certain amount in a certain time while driving full power (when it is close to goal temp it typically runs well below full power):
Firmware
Version
14.09 - does not have the feature
14.12 oct 16, 2014 - feature introduced. 20C in 20 Seconds
14.12.1 dec 15, 2014 - from 20C to 10C (still in 20 seconds)
15.01 jan 14, 2015 - from 20 secs to 30 secs (now 10C in 30 seconds)