Maybe contacts of contactor was welded, which lead the heater run continuously, therefor the temperature exceeds the setting value of EGO and the alarm happens.

Alarm of E-09 stands for honeycomb rotor fault, the possible cause is that transmission part or detector were broken. It is possible to fix it according to following steps:
1.Check parameter F-19 whose default value is about 600s, if this parameter was set at a over smaller number, this alarm happens.
2.If F-19 is normal, disassembly left side plate, move rod of microswitch near rotor and alarm will reset automatically, then confirming if rotor rotates normally, if it runs normally, maybe detecting circuit is broken, otherwise transmission part is malfunctioned.
3.Confirming if the micorswitch could be switched ON/OFF normally by top point of block on honeycomb rotor, if not, adjusting position of microswitch until it can be turn ON/OFF regularly.

Please pay attention to confirm whether the surrounding air enter into the system. You can observe the change of dewpoint when the inlet of dehumidifier connects directly to outlet of itself.
Check the return air temp, usually it is lower than 35℃.
Check the pipeline whether there is gas leakage.
Check the dew point sensor and monitor if they are broken.