Smeg WDI12C6 new door lock fitted but still error code E13

Hi there. I have a Smeg WDI12C6 washer dryer. Recently I had error code E13 come up at the end of a wash cycle and the machine will not start and the solenoid is clicking in and out multiple times. I replaced the door interlock and his has not resovled the problem. On further inspection with a multimeter at the PCB end of the door lock wiring loom I can see that the door lock is operating properly, I.e. 2 terminals go open and closed circuit when machine door is locked unlocked with the solenoid.
I have seen reference to disconecting heater wiring, but I cannot see how that would affect the door lock?
What should I do next, a new PCB? I am reluctant to do this as it feels like throwing good money after bad as PCBs tend to be expensive.
I would be grateful for any help or suggestions, many thanks in advance!