68
Errors (red screen)
On the display, errors found are shown
in the form of a message or blocking
on a blue screen or an error on a red
screen.
- Blocking
This is a temporary error that will
sort itself out, or it will block the
boiler after several attempts (error)
(Except: Bx01sc01 = reset)
- Error
Error implies a blocking of the boiler
and can only be solved by a reset
and/or intervention of a service
engineer.
- Message
Implies a message such as low
water pressure, but the device will
remain operational.
Point of attention requiring short-
term intervention.
The code consists of a Main Code and
a Subcode
Main code Blocking
=
B
Main code Error
=
E
Main code Message
=
M
Followed by a character
0
= boiler
1
= burner A
2
= burner B
Subcode always starts with
sc
Bx01sc01
Fan does not run on correct speed (Reset necessary).
Fan
defective.
Bx03sc01*
Flow sensor T1 open
Bx03sc02*
Flow temperature T1 too high
Bx03sc03*
Flow sensor T1a open
Bx03sc04*
Flow temperature T1a too high
Bx05sc01*
Return sensor T2 open
Bx05sc02*
Return temperature T2 higher than flow temperature
Bx08sc01*
General purpose contact open
Bx12sc01*
Water pressure sensor open
Bx12sc02*
Water pressure sensor closed
Bx12sc03*
Water pressure lower than 0.7bar. Top up
Bx12sc04*
Water pressure too high. Decrease pressure
Bx12sc05*
No pressure increase on pump start
Bx13sc01*
D
T between T1 and T2 too high
Bx15sc01*
Communication error between controls
Ex01sc01*
Fan does not run on correct speed. Fan defective.
Ex02sc01*
No flame after 4 start attempts
Ex02sc02*
Insufficient ionisation
Ex04sc01*
Flow temperature T1 too high
Ex04sc02*
Flow sensor T1 closed
Ex04sc03*
Flow temperature T1a too high
Ex04sc04*
Flow sensor T1a closed
Ex06sc01*
Return temperature T2 higher than flow temperature
Ex06sc02*
Return sensor T2 closed
Ex18sc01*
Flame detected when burner should not be operating
Ex14sc01*
D
T not fast enough
Ex14sc02*
D
T between T1 and T2 > 35°C
M024sc01
DHW sensor T3 open (when P122=1)
M024sc02
DHW sensor T3 closed (when P122=1)
M024sc03
Outside sensor T4 open
M024sc04
Outside sensor T4 closed
M024sc05
Common flow sensor T10 open
M024sc06
Common flow sensor T10 closed
M024sc08
Bus communication:
Possibly no bus communication cable connected
Mx24sc09
Temperature increase (Gradient) not fast enough
after burner start
Mx24sc10
D
T between T1 and T2 > 35°C when gas valve opened
Mx24sc11
Service required
* When this code is shown with an M instead of a B or E then a reset with the reset
button is possible.
OpenTherm error messages
The coding of the transmitted Error Messages on a OpenTherm controller is
displayed as follows:
(E) EB (E = Error Code = B and boiler number)
example: Error Code Ex02SC02 on boiler 6 will appear as (0) 26
Block.
B000sc00
Error
E000sc00
Message
M000sc00
