Bosch BGH96M060B3B Installation Instructions Manual page 53

Symptoms of
Fault
Abnormal Fault Description(s)
Code
Operation
— No 115 volt
power to
furnace, or no
24 volt power to
integrated control
None
Furnace fails
module
or
to operate
— Blown fuse or
FO
circuit breaker
— Integrated control
module has an
internal fault
— Flame sensed
Furnace fails
FE
to operate with gas valve off
— Pressure switch
Furnace fails
E1 closed with
to operate
inducer off
— Low fire pressure
Induced draft
switch open with
blower runs
inducer on
continuously E2
— Pressure switch
E4
with no
cycle lockout
further E3
— High fire pressure
furnace
switch open with
operation.
high inducer on
— Limit/RoIIout
switch open less
than 5 mins
— Limit/RoIIout
Furnace fails E5
switch open more
to operate. E6
than 15 mins
— Limit/RoIIout
switch open from
5 to 15 mins
Table 27
Troubleshooting Chart
Bosch 96% AFUE Condensing Gas Furnace - BTC 770503101 J (06.2023)
Possible Reason
— Door switch open, or 24 volt
wires improperly connected or
loose.
— Blown fuse or circuit breaker
— Integrated control module has
an internal fault
— Short to ground in flame sense
circuit.
— Induced draft blower pressure
switch contacts "stuck".
— Shorts in pressure switch circuit.
— Pressure switch hose blocked,
pinched or connected
improperly, blocked flue, or
weak induced draft blower.
— Incorrect pressure switch
setpoint or malfunctioning
switch contacts.
— Loose or improperly connected
wiring.
— Faulty chamber limit switch or
fan mounted limit switch.
— Insufficient conditioned air over
the heat exchanger. Blocked
filters, restrictive ductwork,
improper circulator blower
speed or failed circulator
blower
— Misaligned burners, blocked
flue, or failed induced draft
blower.
— Faulty rollout switch - resettable.
— Faulty inducer.
— Loose or improperly connected
wiring.
Corrective Action
1. Assure 115 and 24 volt power to
furnace's integrated control module.
2. Check integrated control module's
fuse (3A). Replace if necessary.
3. Check for possible shorts in 115 and
24 volt circuits. Repair as necessary
OR replace bad integrated control
module.
1. Correct short at flame sensor or in
flame sensor wiring
1. Replace induced draft blower's
pressure switch.
2. Repair short.
1. Inspect pressure switch hose.
Repair if necessary. Inspect flue for
blockage, proper length, elbows, and
termination.
2. Replace pressure switch.
3. Tighten or correct wiring connection.
1. Check chamber limit switch or fan
mounted limit switch. Replace if
necessary.
2. Check filters and ductwork for
blockage. Clean filters or remove
obstruction. Check circulator blower
speed and performance. Correct
speed or replace blower if necessary.
3. Check burners for proper alignment.
Check flue and air inlet piping for
blockage, proper length, elbows and
termination. Correct as necessary.
4. Check rollout switch - resettable.
Replace if necessary.
5. Check induced draft blower for proper
performance. Replace if necessary.
6. Tighten or correct wiring connection.
Installation Instructions
Cautions And Notes
— Turn power OFF prior to repair.
— Replace integrated control
module's fuse with 3A
automotive fuse.
— Read precautions in
Electrostatic Discharge
section of manual.
— Turn power OFF prior to repair.
— Turn power OFF prior to repair.
— Replace pressure switch with
proper replacement part.
— Turn power OFF prior to repair.
— Replace pressure switch with
proper replacement part.
— Turn power OFF prior to repair.
— Replace pressure switch with
proper replacement part.
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