Do you mean light 3 flashing? ( not error code 3)
Error code 03 would be lights 2+3 flashing.
It could be any of the following,
Inlet valve, connections, heater open circuit,
heater earth fault, etc.
As I mentioned in an earlier post, earth faults on the heater or motor are often the cause of error messages on these machines.
That which can be asserted without evidence, can be dismissed without evidence.