• Viessmann Boiler Fault Codes

Listed below are Viessmann boiler fault codes and Viessmann boiler Manuals.

Fault Code
Boiler Behaviour
Possible Cause
02 Burner control switches to lockout Safety chain was activated
 04, 05, 06, 08 Burner control switches to lockout Fan speed too high/low at start
07, 09 Burner control switches to lockout Basic level of air pressure threshold in standby mode not correct
0A Burner control switches to lockout Fault, fan speed
0d Burner control switches to lockout Reset button pressed repeatedly or while burner is running
1A, 1B Burner blocked Flow sensor 1, 2 Faulty
1F Burner blocked Differential flow rate too large
25 Boiler operates with high boiler water temperature Emissions test switch turned to “hand symbol” for 30 minutes already
26 Boiler operates with continuous relay test Setting mode for maximum or minimum rated input active for 30 minutes already
35 Boiler does not activate Reset button (pressed while burner is OFF) with Emissions test switch turned to “hand symbol”
A2 N/