Viessmann Vitoligno 200-S Installation And Service Instructions Manual page 64

Troubleshooting
Fault display
(cont.)
Fault code dis- System characteristics
played
90
91
64
Cause
Fuel too damp
■
Lambda probe inaccu-
■
rate
Logs poorly charged
■
Lambda probe heavily
■
soiled
Lambda probe faulty
■
PCB fault
■
Measures
Use suitable dry fuel
■
Recalibrate the Lambda probe
■
(see page 67)
Acknowledge with
d
■
Recalibrate the Lambda probe
■
(see page 67)
Acknowledge with
d
■