ecoTEC pro - Vaillant

13 Troubleshooting
Code Meaning Cause
F.68 Unstable flame signal fault Air in gas, gas flow pressure too low, wrong air ratio, condensate route
blocked, wrong gas restrictor, ionisation flow interruption (cables, electrodes),
flue gas recirculation, condensate route
F.70 Invalid device specific number (DSN) Spare part case: Display and PCB changed at the same time and appliance
code not reset
F.71 Flow NTC fault Flow temperature sensor signalling constant value:
- Flow temperature sensor incorrectly positioned at supply pipe.
- Flow temperature sensor defective.
F.72 Flow/return NTC fault Flow/return NTC temperature difference too great -> flow and/or return
temperature sensor defective
F.73 Water pressure sensor signal in the wrong range
(too low)
F.74 Water pressure sensor signal outside correct
range
(too high)
F.75 Fault, no pressure change detection when starting
pump
F.76 Overheating protection on primary heat
exchanger has responded
Interruption/short circuit of water pressure sensor, interruption/short circuit
to GND in supply line to water pressure sensor or water pressure sensor
defective
Cable to water pressure sensor has short-circuited at 5 V/24 V
or internal fault in water pressure sensor
Water pressure sensor and/or pump defective, air in heating installation,
too low water pressure in boiler; check adjustable bypass, connect external
expansion vessel to return
Cable or cable connections for safety fuse in primary heat exchanger or
primary heat exchanger defective
F.77 Flue non-return flap/condensate pump fault No response from flue non-return flap or condensate pump defective
F.78 Interruption to DHW outlet sensor at external
controller
UK link box is connected, but hot water NTC not bridged
F.83 Flow and/or return temperature sensor temperature
change fault
F.84 Fault: Flow/return temperature sensor temperature
difference implausible
F.85 Fault: Flow and return temperature sensors incorrectly
fitted
connection
When the burner starts, the temperature change registered at flow and/or
return temperature sensor is non-existent or too small.
- Not enough water in the boiler
- Flow and/return temperature sensor not in correct position at pipe.
Flow and return temperature sensors returning implausible values.
- Flow and return temperature sensors have been inverted.
- Flow and return temperature sensors have not been correctly fitted.
Flow and/or return temperature sensors
have been fitted to the same pipe/wrong pipe.
No communication with the PCB Communication fault between display and PCB in the electronics box
13.2 Fault codes (continued)
13.3 Running test programs
By activating various test programs, you can trigger special
functions on the boiler (¬ table. 10.1). The display shows
which test program you have chosen.
> Read how to start the test programs in ¬ section 10.2.
13.4 Resetting parameters to factory settings
As well as the option to manually reset individual parameters
to the default settings specified in ¬ table 11.1, you can
also reset all parameters at once.
> Set the value of the diagnosis code parameter D.096 to
"1" (¬ section 11.1).
You have now reset all parameters to factory settings.
58 Installation and maintenance instructions ecoTEC pro 0020129672_03