Miele W838 washing machine: main wash light flashing

[Nigelfr]

From perusing many forums, it appears that when the main wash light keeps on flashing this means there is a fault in the heating circuit. The manual says switch off and try again. Did that, same problem. Contacted Miele who said call out a technician. Well only as a last resort, so decided to take a look inside.

First thing I disconnected the machine from the mains. After opening the front (3 screws in detergent tray surround, 3 bolts around the door, emergency drain hose and the clip on the bottom left corner), I checked the resistance across the heater element: 25 ohms and also across the NTC: about 20k ohms at about 12°C. Took out the heater relay and checked it with 12v across the terminals: it worked. Checked the continuity of the leads from the mains supply board to the relay, relay to heater element, NTC to circuit board and circuit board to relay: all OK.

Started a 40°C wash cycle and added really hot water to the machine through the detergent tray as it started to fill. The main wash light stopped flashing.

So what's the conclusion? Problem on the circuit board? During a wash just before this problem started there was a huge unbalanced spin where a duvet cover swallowed all the other washing. Could this have caused something to fail on the PCB? Or maybe caused a crack in the soldering? I would like to take the PCB out to check it, but don't know how, so some advice on that would be gratefully received.

 

[zipper]

To remove the pcb take off the program selector (pulls/levers off). Then using a thin knife lever the upper RH side of the control fascia carefully down & forward. Once slightly out of its seating move the knife to the left until it pops out completely. Two T20 screws underneath & you're there. You could still have a problem with the NTC even if it measures 20k at 12C (which is about ball-park for that temp). You could try removing & checking it hot. At 70C the resistance should drop to around 2 - 2.5k.

 

[Nigelfr]

Thanks Zipper. It looks like it won't be necessary, as the machine is now working fine.

Maybe it was a loose connection that I fixed when I was taking the wires off to check their continuity. However, the flashing light only stopped after I had put the hot water through the machine via the detergent tray. Maybe it needed that high temperature to reset the fault?

 

[zipper]

It is sometimes possible to "shock" an NTC back into function by popping it into very hot water. But it will fail again sooner or later.

 

[JP777]

I have w833 and the main wash light flashes sometimes. When it first did it I took the heater relay off, cleaned it’s contacts as I got the impression the heater was remaining on in the rinse cycles. Cured it for some time. Now doing it again even when first switching on. Machine still works ok but now suspect that it may be not heating, although the time I tried it it did heat (felt the door) and of course the light stopped flashing. Time to clean up the relay again I think.