Smeg Washing Machine - Error 4

[flash68]

Hi, I have a Smeg washing machine, WM63141BK, which I bought a couple of months ago second hand.

Yesterday it began reporting an error 4 (which I believe to be a thermister fault according to a document on the Smeg website).

It begins the program, takes in water, makes a churning noise without the drum rotating then a few minutes later shows error 4 and stops.

It will not complete any wash or spin cycles, only drain.

I tested the thermister and it appears to be working. Initially reading 26KOhms at room temperature, dropping to 19K in warm water and rising beyond 26K in iced water.

I've also tested the heating element for continuity - there is continuity between the outer 2 of the 3 terminals, no continuity between either outer terminal and the middle terminal.

If the fault is the termister, would that really affect the spin cycle since it is not heating water?

Something that may or may not be relevant. Out of necessity (due to current restriction with access) I had to plumb this cold fill machine into the hot supply. I've read the articles on here about the issues with this and intend to attach to the cold supply as as soon as possible. I'm only mentioning it in case it makes a difference. Although it has been working fine on the hot supply for a while and I have tried again after allowing the hot supply to go cold and I still get the error 4.

[Whitegoodshelp (Andy)]

Yes it seems that Smeg generally use error 4 or E4 error to indicate a fault on the thermistor. It isn't possible to accurately test a thermistor without knowing what resistance readings should be seen at the varying temperatures but I would normally suspect one is OK if it is giving varying readings at different temperatures. I suppose it is theoretically possible that the wrong readings could throw up an error but whether in practice they ever go faulty in a way that causes inaccurate readings I don't know.

I've had cases where error codes have pointed to a part which I then replaced only to find the fault remained so error codes aren't always 100% reliable. If there is genuinely a fault on the thermistor it can range from being faulty inside, short circuiting inside, maybe a crack somewhere? to connection faults on the thermistor itself and potentially even breaks in the wiring or connection faults between the wires coming out of the thermistor anywhere down to where it connects to the pcb board. So if for example there was a connection fault or a damaged or broken wire at the pcb it would appear open circuit to the machine.

Regarding connecting it to the hot water supply, I expect it might confuse the washing machine if the wash water is starting hot when it expects it to be pretty cold but I wouldn't expect it to cause a fault as such. It should cause problems with the laundry not washing for long enough, less than ideal wash results (especially with biological detergent) and potentially creased laundry all of which (and more) are explained in my article which I'll link to in case anyone else is interested - can you connect a cold fill washing machine to the hot water tap?

[flash68]

Thanks for your reply.

Smeg customer services confirmed that error 4 was the thermister so I ordered a replacement but the error was still there.

I checked the resistance on the heating element and it checked out ok. I then checked the resistance across each pair of pins on the motor plug in turn and it showed that one of the carbon brushes was an open circuit.

The brushes were very low and after scraping the brush it showed a resistance and the error vanished and the machine was working again.

I'm not sure why the error 4 was showing when the problem was the motor, very misleading.

[Whitegoodshelp (Andy)]

Thanks for the update, your experience validates my advice that error codes can be unreliable. It's ridiculous how unreliable they can be.