Vaillant ecoTEC plus 937, Instructions And Maintenance Instructions, Page: 51 / 64

51 Installation and maintenance instructions ecoTEC plus 0020031552_03
Code Meaning Cause
F.81 APC loadpump fault connected to F.91
Storage tank is not fully charged after a specific period of time.
-Check storage tank charge sensor and storage tank sensor
-Air in the APC pump
-Check pump wiring harness
-Secondary heat exchanger blocked
-Priority changeover valve defective
-Pump defective
F.90
Communication with shift load storage tank module
interrupted
Check wiring harness from combi boiler to shift load storage
tank (PE Bus). If combi boiler is to be operated without shift load
storage tank, set d.92 = 0
F.91 Sensor error on shift load storage tank module (NTC)
NTC faulty, NTC cable faulty, faulty plug connection on NTC,
faulty plug connection on the electronics
con No communication with the printed circuit board
Communication fault between the display and the printed circuit
board in the electronics box
Table 8.4 Error codes
8.2 Test programmes
Special functions can be triggered in the appliance by
activating various test programs.
These programmes are listed in detail in Table 8.5.
• The test programmes P.0 to P.6 will be started when "
Power ON“ is turned on and the " + “ button is pressed
for 5 seconds simultaneously.
The display shows "
P.0 “.
• Press the " + " key to start counting the test pro-
gramme number upwards.
• Press the " i “ to operate the appliance now and to
start the test programme.
• To de-activate the setting mode, simultaneously push
the buttons " i “ and " + “. You can also end the test
programmes by not pushing any button for a 15 minute
period.
Display Meaning
P.0
Bleeding test program The heating circuit and
the hot water circuit (only on combination boilers)
are bled via the automatic air vent (the cap of the
automatic air vent must be released two turns).
P.1
Test programme where the appliance is operated
in full load after successful ignition.
P.2
Test program where the appliance is operated
with minimum gas volume (ignition gas volume)
after successful ignition
P.3 not available
P.4 not available
P.5
Test programme for checking the safety tempe-
rature limitation: The unit is heated by avoidance
of the regular switch-off by the feed regulator until
a temperature of 97 °C is reached.
P.6
Filling programme: The diverter valve moves to
the centre position.
Table 8.5 Test programmes
8.3 Resetting the parameters to factory settings
Besides the option to reset individual parameters
manually to the factory settings specified in Tables 9.2
and 9.3, you can also reset all parameters simultaneously.
• In the second diagnostic level, under the diagnostic
point " d . 96 " change the value to 1 (see Section 8.1.2).
The parameters of all adjustable diagnosis points now
correspond to the factory settings.
Troubleshooting 8