FAUL
T CODE THUMBNAILS –
PAGE
F 5
FAUL
T CODE THUMBNAILS –
PAGE
F 5
Heater System Solving Guide
Fault Code Thumbnails BO
Bypass Operation (for e
xternal controls)
F
AULT
C
ODE
T
HUMBNAILS
BO B
YPASS
O
PERATION
(
FOR
EXTERNAL
CONTROLS
)
BO
B
YPASS
O
PERATION
(F
OR
E
XTERNAL
C
ONTROLS
)
UHS, IDL2, IDL, ED2
The “bo” code is more of an information code than a fault code,
with the “bo” standing for Bypass Operation.
A “bo” code indicates the heater’s internal thermistor is disabled,
allowing the external thermostat control to operate.
This prevents any confusion between the two temperature-sensing
devices during heater operation — though the heater’s thermistor
will still prevent the heater for exceeding 104
o
F.