I get lots of mould on the door seal - why? The machine also leaks when its empty or only half full

Have you tried putting the machine on a boil wash, with just bleach in the water ( and no clothes)? That should work, but it the door seal is discoloured by the mould, then the only practical solution is to replace the door seal.
I hope this helps?

If you look in manual there is a clean setting. You use one cup of bleach and run this cycle, Remember to leave the door open when you are not using it so that it dries out between loads.

the tub beneath the washer is full and is not draining. the clothes have probably opened up the seal between the door and washer allowing water to leak. tip the machine and empty the sump to clear error.

Confirm that it is not the door seal. The door seal can easily be replaced and the parts are available.

You would expect that any water leaking around the door seal would migrate down to the lowest part of the tub leaving the appearance that the leak is where the two half's of the tub are joined by the retaining clips
.
Replacing the seal between the two tub half's is a different story as compared to the door seal. The tub seal is definitely do-able, but not for the faint of heart!!
Washer Tub Seal Replacement Frigidaire Front Load Washing Machine Repair...

If the leak is very very small I might wait until a major overall is require such as the tub seal/bearing. If I chose to wait I would monitor the situation.

Inspect the area at the hub of the pulley looking for streaks of rust.. If there is an indication that water is leaking past the basket tub seal than doing an over hall now may included front door seal, tub seal, bearing and basket seal replacement.

Don't use eucalyptus oil, because it will damage the rubber, and the smell will linger.
The black mould should be wiped off using a damp soft cloth and mild detergent. Diluted bleach (1 part in 10 parts cold water) can also be used, with care (wear gloves); don't use full-strength bleach, because it can damage rubber and corrode metal. Leave the door and detergent drawer open between washes and overnight to keep air circulating through the machine. This will slow down the regrowth of mould. For further improvement, wipe the seal dry after each use of the machine. If your laundry room remains steamy or damp for hours after washing, improve the ventilation

This video will show you how to change a door seal on this Bosch washing machine

Leaks coming from the actual machine can be caused by component failure such as the door gasket, various hoses, the pump, or from defective or loose seals or joints.

hi, has the seal been replaced?if not use an old tooth brush and clean it with tooth paste it will clean off the mould, if the seal has been replaced check around the rim for a drain holle it may have been fitted wrong, some dont have drain holes hope this helps

There are several reasons for this to happen.
the primary one is the fact that you are doing a lot of low temp washes, and this causes a build up of grease and dirt around the door seal, the mould you refer to is actually bacteria.
You must do a high temp wash at least once every 6 to 8 weeks, put powder and or detergent in as usual, but no washing, and let it do a full cycle.
This is called a maintenance wash and helps prevent what has happened to your m/c.
Thoroughly clean the door seal with a scouring pad or stainless steel wool, you will not harm the seal,
You will probably find the seal will be stained, but as long as you get all the mould etc off, it will be o/k.
Plz rate my solution.
Thanks

what sort of soap powder do you use
some soap powders foam a lot in machine causing dishwasher to leak through seals
also check that the machine is square that is the door is closing parallel with cabinet
do not use power balls in machine just standard dishwasher detergent and separate rinse aid