39
Remove multiway
connector from board
position
ST16
. Test
resistance across
contacts
15
and
16
(black & yellow wires).
Is it between 1 kOhm
and 30 kOhm?
Test resistance across
contacts
12
and
13
( red & black wires). Is
it between 1 kOhm
and 30 kOhm?
Is there continuity
from individual
contacts
15
and
16
to
DHW sensor?
Check or replace
DHW sensor.
Is there continuity
from individual
contacts
12
and
13
to
CH sensor?
Repair or replace
harness.
Repair or replace
harness.
Is the multiway
connector at board
position
ST16
pushed
fully home on to the
board?
Push fully home
No
No
No
No
No
Yes
Yes
Yes
Check the DHW
sensor. Is it correctly
fitted onto the pipe
with heat conductive
paste between the
pipe and sensor?
Yes
No
Re-fix sensor onto pipe
Is the Code plug fitted
and
fully home?
Fit/push fully home
Yes
No
TEST E
Check or replace
CH sensor.
Test resistance across
contacts
13
and
14
(black & blue wires).
Is it open circuit?
Turn off electrical
supply.
Remove fan connector
from board position
ST1
.
Test resistance across
contacts to black &
white cables.
Is it between 75 and
175 ohms?
Check/repair fan
harness or repalce fan.
Air pressure switch
is shorting.
Check tubes for
blockage or replace
switch.
No
No
Yes
Yes
Yes
Test resistance across
contacts to black &
red cables. Is it
between 20 and 60
ohms?
Yes
Yes
No