Vaillant Turbomax plus hot water problems running out of ideas fast

[drips.drops]

so I have changed...

diverter valve
h/w heat exchanger
thermistor
aqua sensor
code coming up is s.54 flow gradient too steep

after speaking with vaillant suggesting that only other option Is pcb

ordered PCB for tomorrow

has anyone else had massive issue with these or just me?
Boiler is only 5 years old??

any help would be great only thing I can think will help is powerflush as no magnaclean or similar fitted?
​

 

[Ermintrude]

Yeh gas appliance rules.......

 

[kris]

Thats alot of parts changed mate , cant give out info on gas related subjects unless your proven gsr registered and in private forum, if you are gsr reged then get your post count up to 10 then contact one of the moderators on here then help will be given,

 

[Dotty]

Read the forum rules with regards to gas appliances.

Thank you.