Bosch SMS53A12GB/51 dishwasher E17 fault.

Bosch SMS53A12GB/51 dishwasher. FD9206.

This machine was clogged with sludge due to lazy customer not cleaning the filter… possibly ever. 😡 The original fault was for a E24 error. Cleaned out the sump, pump, and outlet hose; machine started OK – E24 gone. There is an additional tank on the right side of this machine that was coated internally with brown sludge so as best as I could I removed it (and its actuator wax solenoid) and flushed it through – also cleared the pipe that joins it to the diverter valve nozzle. Refitted it and ran machine.
Starts program, runs drain pump, then revs wash motor for a few seconds, blips fill valve to test water flow, fills for about 10 seconds then 001 in the display, drains out – E17. Couldn’t solve it so pulled into workshop as pushed for time.
Ran the machine in the workshop and it worked fine. 😮 I recleaned the machine and it went through a further 4 times with no issues. The aforementioned tank (687955 ‘liquor tank’ as BSH call it!) remained empty until the final 2 minutes of the cycle when it filled up and the cycle finished. The tank remained full until the machine was started on a new program: the tank would drain down as the wash pump was doing its initial run up and then the machine would drain out and refill as normal then do a perfect cycle.

What does this tank actually do? Is it only used to prime the wash pump to get a reading for the module; if so, why aren’t all BSH d/w’s fitted with them? Otherwise I really can’t see what their purpose is. BUT if that tank is empty then the E17 ( no fill) error appears…….. arrgghh!
Any help on this please??

Cheers,

Steve.