Hi, could be the hot water temperature sensor. If the sensor is faulty it would prevent the boiler firing up.definitely replace it
E04 is faulty temperature probe, but if you have replaced it have you replaced the hot water flow switch ?
Does the boiler fire up when you run a hot tap? Even for a few seconds
Hi, no I don't th9nk so . I wonder if you got a faulty new temperature probe. If you have a multimeter you can test the probe using ohms setting .the reading should change on temperature change.
Well most of the parts that are on the hot wTer side have been changed so the pcb is a possibility, but would definitely check the hot water temperature probe first.
By the way it is possible to get reconditioned pc's which are half the price.