D Overview Of Fault Codes - Vaillant ecoTEC plus VU GB 656/4-5 A Installation And Maintenance Instructions Manual

Status code Meaning
S.24 DHW mode: Burner on
S.25 DHW mode: Pump/fan overrun
S.26 DHW mode: Fan overrun
S.27 DHW mode: Pump overrun
S.28 Hot water burner anti-cycling time
Special cases
S.30 Room thermostat (RT) is blocking heating mode
Summer mode active or no heat requirement
S.31
from eBUS controller
S.32 Waiting period because of fan speed deviation
S.34 Frost protection mode active
S.36 Reference setting for the continuous controller 7-
8-9 or eBUS controller is < 20 °C and blocks the
heating mode
S.39 Contact thermostat tripped
S.41 Water pressure > 0.28 MPa (2.8 bar)
S.42 Flue non-return flap return signal blocks burner
operation (only in connection with accessories)
or condensate pump faulty, heat requirement is
blocked.
S.53 Product is within the waiting period of the mod-
ulation block/operation block function as a res-
ult of low water pressure (flow/return spread too
large)
S.54 Product is within the waiting period of the oper-
ation blocking function as a result of low water
pressure (temperature gradient)
S.59 Waiting period: Minimum volume of circulation
water not achieved
S.85 Service message: "Check circulation water
quantity".
S.96 Return sensor test running, heating demands are
blocked.
S.97 Water pressure sensor test running, heating de-
mands are blocked.
S.98 Flow/return sensor test running, heating de-
mands are blocked.
D Overview of fault codes
Code Meaning
F. 0 Flow temperature sensor interruption
F. 1 Return temperature sensor interruption
F.10 Flow NTC short circuit
F.11 Return NTC short circuit
F.13 Cylinder temperature sensor short circuit
F.20 Safety switch-off: Temperature limiter
F.22 Safety switch-off: Low water pressure
F.23 Safety switch-off: Temperature difference too
great
F.24 Safety switch-off: Temperature rise too fast
0020214491_01 ecoTEC plus Installation and maintenance instructions
Cause
NTC plug not plugged in or has come loose, multiple plug on the PCB
not plugged in correctly, interruption in cable harness, NTC defective
NTC plug not plugged in or has come loose, multiple plug on the PCB
not plugged in correctly, interruption in cable harness, NTC defective
NTC defective, short circuit in cable harness, cable/casing
NTC defective, short circuit in cable harness, cable/casing
NTC defective, short circuit in cable harness, cable/casing
Incorrect earth connection between cable harness and product, flow or
return NTC defective (loose connection), black discharge via ignition
cable, ignition plug or ignition electrode
No or insufficient water in the product, water pressure sensor defective,
cable to pump or water pressure sensor loose/not connected/defective
Pump blocked, insufficient pump output, air in product, flow and return
NTC connected the wrong way round
Pump blocked, insufficient pump output, air in product, system pressure
too low, non-return valve blocked/incorrectly installed
Appendix
35