Neff S51T69X1GB (Bosch) Dishwasher E.25 -- not obvious --

[Masterpop]

Hello,

I'm stumped and wondered if anyone could help. I get a E25 drain issue.
Checked machine for blockages/ filter pump
I have thoroughly checked the hose from back of machine into sink drain.
Have checked short transparent hose from water pump to washing machine S bend thinggy (took side off it to have a look)
Replaced water pump.
Not trusting the long hose from back of machine, i unplugged the short hose from water pump and pointed it to a bucket on the side..
It tries three times to shift some water... which it manages, then it gives up and throws the error. I don't understand... So there is the 30cm hose and waterpump (which is brand new).. both are clear.. yet it's not happy...

Is there anything else i can check/clean? Any ideas...Any suggestions much appreciated

 

[Masterpop]

SOLVED:: the out pipe from the dishwasher has a tiny no return valve...I guess the rubber has lost some of its elasticity after 5 years and was getting stuck. Once I removed it I've not had a problem.