Bosch / Siemens Dishwasher - Fix No Heat / Random Stops

I have recently came across a 7 year old dishwasher which was on sale because it did not heat and sometimes did not start the program or did not finish it properly. The washer had the model number SN44T580SK/23 however this problem appears to be common for many similar machines. The machine was checked by Siemens service and a repair quote of about 500€ was given for change of main control unit of the machine.

When we ran the machine in different programs, we found out that m ost of the time the quick wash program was working properly. Few times it game the E.02 error on display. Apparently E02 error is listed as "Running without heating" and cause is "Working relay of heating is defective" and repair advice is "Change power module". However the module itself is quoted over 250€ at Siemens parts site.

First thing to check is if the element is in working condition. This can be done simply using an ohm meter. The instructions are as shown in the picture below.

The control module in questionw as EPG60110 with part number 9000376770. Unfortunately, I read that these modules are programmed to the machine model so you need to find a module removed from exactly same model machine or it wont function even if all the part numbers match.

I removed the module from its plastic housing after removing all the connections. It is a very simple operation. It was in perfect condition (it looked like it was manufactured very recently) and there were no cracked solder joints etc. Below is a picture of the module from top:

The problem resistors are located on the lower side near the large tabs where the heater cables are connected. Below is a close up.

The problem relay model was HF7FD 012-1ZPTF(576) . There are 2 relays because the heating element consists of 2 parts. Perhaps quick wash uses both relays to heat up the water faster and therefore it was working more often (assuming one of the relay was working better).

What we did was to go to the local electronics store and buy a replacement relay. The replacement we found was RELPOL RM50-3011-85-1012 (unit cost ~3€). It is not a perfect match but the best available in such short time. You may want to go with an 12A or 16A resistive load relay if you can find it in a size which is suitable. I have to remind here that The HF7FD model was a 6-pin switch however you can replace it with a 5-pin version of a similar switch. There is only about 2mm space on top of the relay. The original HF7FD relay was of size (Depth x Width x Height) 16 x 22 x 16.4 mm. You may be able to fit another with a maximum height of 18mm. But I didn't try this and since the RELPOL switch was smaller, this was no problem at all. Picture below shows the dimensions of the HF7FD relay.

I used a manual solder vacuum pump to remove the solder from the original relays. It was very easy to vacuum the solder since the board has rather large holes compared to legs of the relay. The pump could pull out the solder easily.

After removal, simply cleaned the holes on the board with electronics cleaner and then soldered the RELPOL RM50 to same places leaving 6th hole empty. I am not exactly sure why the relay needed 6th pin actually. It seemed rather redundant.

For now, the machine works perfectly. No doubt the relays will fail again, but at least now we know how to easily fix it.