40
Replace control board.
In the unlikely event
of this not solving the
problem replace code
plug.
Pressure switch has
opened during
operation.
Check flue for
blockage.
Also investigate sense
tubes and pressure
switch.
Replace fan connector
ST1
.
Remove electrical
connectors from air
pressure switch and
reset/restart boiler.
Is there continuity
between
C
and
NO
terminals (where wires
were fitted) when the
fan runs?
(Test within 30
seconds).
Pressure switch has
not closed. Are the
silicon tubes in good
condition and free of
condensation.
Replace air pressure
switch.
Note: In the unlikely
event of this not
solving the problem
inspect the pressure
pick-up (Venturi) in the
fan or fan may not be
running freely.
Inspect the flue. Is it
free of any
restrictions?
Rectify flue problem.
Does the burner ignite
(burner light on) and
run for a short priod
before the fault
occurs?
Replace control board.
Repair cables or
replace main harness.
Replace tubes. If
condensation has
occurred, also replace
pressure switch and
check condition of
Venturi in the fan.
No
No
No
No
Yes
Yes
Yes
Yes
Turn to 'NORM'
position
The gas valve mode
switch (concealed by
the facia side panel)
is not set correctly
TEST F
Replace multiway
connector to position
ST16
(but not fan
connector at
ST1
) and
reset/restart the
boiler.
Is there mains 230V
across the right (
L
)
and left (
N
) tracks at
board position
ST1
?
NOTE:
Take care not to
short
L
to
N
.
Yes
Remove multiway
connector from board
position
ST16
.
Is there continuity of
black & blue cables to
the air pressure
switch?
No
No
Yes
Yes