Diagnostic Codes - Vaillant ecoTEC plus Instructions For Installation And Servicing

Display Meaning
Charge hot water cylinder (when accessories are
fitted):
S.20 Warmstart demand
S.21 Fan running
S.22 Pump running
S.23 Ignition sequence
S.24 Burner ignited
S.25 Fan and water pump running
S.26 Fan over run
S.27 Pump over run
S.28 Anti cycling mode
All boilers:
S.30 No heating demand from external controls (clamp
3-4 open)
S.31 Central heating thermostat knob turned off or no
heat demand by the eBUS control unit
S.32 Heat exchanger antifreeze active, as fan speed
variation is too high. Appliance is within the waiting
time of the operation block function
S.34 Anti frost mode active
S.36 No heating demand from low voltage controls
(clamp 7-8-9)
S.41 Water pressure > 2,9 bar
S.42 Response from accessory module or defective
condensate pump is blocking burner operation
S.53 Appliance is within the waiting period of the
operation block function due to water shortage (VL-
RL spread too big)
S.54 Appliance is within the waiting period of the
operation block function due to water shortage
(temperature gradient)
S.96 Return-sensor check is running, demand (DHW or
heating) is blocked
S.98 Flow-/Return-sensor check is running, demand
(DHW or heating) is blocked
Table 10.1 Status codes (continued)
Installation and Servicing ecoTEC plus
10.1.2

Diagnostic codes

In the diagnostic mode, you can change certain
parameters or display more information. The
diagnostic information is divided into two diagnostic
levels. The second diagnostic level can be reached only
after entering a password.
Caution!
Access to the second diagnostic level must be
used exclusively by a qualified technician.
First Diagnostic level
• Press the "i" and "+" keys simultaneously.
The display shows "d.0".
• Use the "+" or "–" keys to scroll through the desired
diagnostic numbers of the first diagnostic level (see
table 10.2).
• Press the "i" key. The display shows the relevant
diagnostic information.
• If necessary, use the "+" or "–" keys to change the
value (display flashes).
• Save the new value by holding down the "i" key for
approx. 5 seconds until the display no longer flashes.
You can end the diagnostic mode as follows:• Press
the "i" and "+" keys simultaneously.
• Do not press any key for approx. 4 minutes.
The current heating flow temperature appears in the
display again.
Second diagnostic level
• As described above in the first diagnostic level,
scroll through the diagnostic number d.97.
• Change the displayed value to 17 (password)
and press the "i" button. You are now in the second
diagnostic level where all information from the
first diagnostic level (see table 10.2) and the second
diagnostic level (see table 10.3) is displayed.
Scrolling and changing values and exiting the
diagnostic mode is done as described in the first
diagnostic level.
Note!
After exiting the second diagnostic level, if
you press "i" and "+" within 4 minutes, you
will directly reach the second diagnostic level
with out having to enter the password again.
Troubleshooting 10
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