Vaillant home combi Installation And Maintenance Instructions Manual page 37

Fault code Meaning
F.83 Fault: Burner temperature sensor
F.84 Fault: Flow/return temperature sensor
F.85 Fault: Temperature sensor
F.86 Fault: Underfloor heating contact
F.87 Fault: Ignition electrode
F.88 Fault: Gas valve
F.89 Fault: Pump
0020224355_00 HOME Installation and maintenance instructions
Possible cause
Burner temperature sensor is defective
When the burner starts, the temperature change recorded by the flow or
return temperature sensor is non-existent or too small: Insufficient water in
the product, flow or return temperature sensor incorrectly attached to the
pipe
Values not consistent, difference < -6 K
Flow and return temperature sensors signalling implausible values: Flow and
return temperature sensors have been inverted, flow and return temperature
sensors have not been correctly installed
The flow and/or return temperature sensors have been installed on the same
pipe/incorrect pipe
Temperature sensor not connected or is connected incorrectly
Underfloor heating contact open, sensor disconnected or defective
Ignition electrode not connected or not connected properly, short circuit in
the cable harness
Gas valve not connected or it is connected incorrectly, short circuit in the
cable harness
Pump not connected or it is connected incorrectly, incorrect pump connec-
ted, short circuit in the cable harness
Appendix
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