Operating instructions

ManualsBrandsViessmann ManualsBoilerType B2HA

116

Dis-

played

fault

code

Const. Weath.-

comp.

System char-

acteristics

Cause Measures

A7 X Control mode

as per deliv-

ered condition

Programming

unit faulty

Replace program-

ming unit

b0 X X Burner blocked Short circuit,

flue gas tem-

perature sen-

sor

Check flue gas

temperature sen-

sor

b1 X X Control mode

as per deliv-

ered condition

Communica-

tion fault, pro-

gramming

unit

Check connections

and replace pro-

gramming unit if re-

quired

b5 X X Control mode

as per deliv-

ered condition

Internal fault Replace the control

unit

b7 X X Burner blocked Boiler coding

card faulty

Plug in boiler cod-

ing card or replace

if faulty

b8 X X Burner blocked Lead break,

flue gas tem-

perature sen-

sor

Check flue gas

temperature sen-

sor

bA X Mixer regulates

to 20 °C flow

temperature.

Communica-

tion error, ex-

tension kit for

heating circuit 2

(with mixer)

Check extension

kit connections and

code.

bb X Mixer regulates

to 20 °C flow

temperature.

Communica-

tion error, ex-

tension kit for

heating circuit 3

(with mixer)

Check extension

kit connections and

code.

Troubleshooting

Fault codes

(cont.)

5772 909 GB