Flashes (System Lock-Out Due To Failed Ignition); Flashes (System Lock-Out Due To Too Many Flame Dropouts) - Bosch BGH96 Troubleshooting Manual

1 0 | Bosch 96% AFUE Gas Furnace

3.2 7 Flashes (System Lock-Out due to Failed Ignition)

8 Flashes (System Lock-Out due to too Many Flame Dropouts)

Troubleshooting Chart
Unit should
work No
normally
Yes
Is gas valve
switched to
"On" position?
No
Yes
Turn the gas
valve switch
to "On"
Replace the
PCB No signal to the gas valve?
board
Check
incoming gas
Yes
supply meet the requirement?
quality
Adjust gas valve
to ensure it
Yes
meets gas
pressure
requirement
Replace the gas
valve if the
pressure cannot
be adjusted
Data subject to change
Start
Are there any
loose wires or wrong
Yes
connections?
No
Does the
unit show 1 LED flash
after restart?
Yes
Is the
ignitor "glowing"
No
red/orange?
Is there a flame?
Yes
(visual check)
No
Is there a
See Figure 10
Yes
Does the
manifold gas pressure
No
See Table 1
No
Is the inlet gas
pressure meeting the
requirement? See
Table 2
No
Adjust the
inlet gas
pressure
Correct wiring
according to
wiring diagram
Replace the
ignitor
No
Is the
ignitor working
Yes
properly? See
Figure 8
Is flame
reaching the flame
Yes
sensor? (visual
check)
No
Are orifices
blocked or clogged?
(check burner)
Yes
Remove
the
blockage
The flame sense signal should be 1-6 microamps.
Troubleshooting Guide
Replace the
PCB Board
No
Check the wire
Is there
power to the ignitor? Yes
See Figure 9
Is the flame
sensor dirty or
Yes
broken?
No
Is the wire
grounded properly? No
See Figure 11
Yes
Replace the
PCB
board
01.2019 | BTC 770502101 A
connections
between
ignitor and
PCB Board
Clean with
steel wool or
replace the
flame sensor
Properly
ground the
wire