Viessmann VITOCROSSAL 200 Service Instructions Manual page 41

Diagnosis
(cont.)
Fault code System character-
istics
F AB Fan does not run
F AD The gas pressure
limiter signals no
gas pressure during
the safety time
F AE Burner control unit
in fault state
F AF Burner control unit
in fault state
F A0 and Status duration too
F A1 long, fan ramp up
F A2 Burner control unit
in fault state
F A3 No password en-
tered for parameter
memory stick
F A4 and Burner control unit
F A5 in fault state
F A6 The ionisation flame
monitor reports ex-
ternal light ingress
during the start or
after the post-purge
F A6 The ionisation flame
monitor reports ex-
ternal light ingress
during the start or
after the post-purge
Cause Measures
Fan faulty; cables Check cables and re-
are faulty or bro- place the fan if required
ken
Gas shut-off valve Open the gas shut-off
closed, gas pres- valve and check the gas
sure limiter faulty supply pressure; clean
the gas filter if required
Valve 1 leaking Replace the gas train
Valve 2 leaking Replace the gas train
Internal fault; fan Replace the burner con-
cannot reach its trol unit or fan
set value
Interruption - Check the safety chain
(strapping plug fJ)
safety chain has
been opened
(strapping plug
fJ)
Values in burner Enter password
control unit and
parameter mem-
ory stick are dif-
ferent; timeout
because pass-
word not entered
Internal error in Replace burner control
feedback from unit
gas safety valves;
output relay does
not respond
Ignition cables Remove the short circuit
shorted out
Ionisation cable Remove the short circuit
or electrode short
circuit
Troubleshooting
41