Vaillant turboMAX pro 24/2 E Instructions For Installation And Servicing page 31

Turn off the main ON/OFF control to the
"0" position
Diconnect the power supply to the boiler
Replace fuse F1
Turn the main ON/OFF control to the "1"
position
Does green power on indicator glow?
Yes
Produce central heating demand.
Does fuse blow immediately?
No
After approx. 20 secs.
Does fuse F1 blow?
No
If fan commences operation, exchange
gas valve
Check operation of pump and fan
No
Yes Check/replace pump
Yes Check/replace fan
Check transformer 230 VAC primary
(black/red) and approx. 17 VDC secondary
(blue/brown)
Yes
Does green power on indicator glow?
No
Replace electronic board
Sheet B
Go to sheet A