Vaillant boiler troubleshooting

The Vaillant company is one of the leaders in production of boilers. The multilevel quality control, original spares, advanced technologies – here are the main features of Vaillant boilers. Unfortunately, its boilers can break down as well. The troubleshooting system provided below in form of a table will help to find the cause of any breakdown.

Vaillant ecoTEC pro boiler troubleshooting

Status codeMeaning
S.00Heating: No heat demand
S.02Heating mode: Pump pre-run
S.03Heating mode: Ignition
S.04Heating mode: Burner on
S.06Heating mode: Fan overrun
S.07Heating mode: Pump overrun
S.08Heating, remaining anti-cycling time xx mins
S.10Domestic hot water requirement via impeller sensor
S.14DHW mode: Burner on
S.20Hot water requirement
S.22DHW mode: Pump pre-run
S.24DHW mode: Burner on
S.31No heat demand: Summer mode
S.34Heating mode: Frost protection
S.46Comfort protection mode, flame loss at minimum load

Product does not start up:
- No hot water
- Heating remains cold
The gas isolator cock installed on-site and/or the gas isolator cock on the product is closed.Open both gas isolator cocks.
The power supply in the building is disconnected.Check the fuse in the building. The product switches on automatically when the power is restored.
The product is switched off.Switch on the product ("Switching on the product" section).
The heating flow temperature is set too low or to the Heating off position, and/or the hot water temperature is set too low.Set the heating flow temperature and hot water temperature ("Setting the heating flow temperature" section/-* "Setting the hot water temperature" section).
The system pressure is insufficient.
Low water pressure in the heating installation (fault message: F.22).
Fill the heating installation ("Filling the heating installation" section).
There is air in the heating installation.Have your competent person purge the heating installation.
After three unsuccessful attempts to ignite the flame, the product switches to fault mode (fault message: F.28).Press the fault clearance key for one second. The product makes another attempt to ignite the flame.
If you have been unable to eliminate the ignition fault after three fault clearance attempts, consult a competent person.
Hot water generation functioning correctly; heating does not start up.The external controller is not set correctly.Set the external controller correctly (-* Controller operating instructions).

Vaillant ecoTEC SERIES  boiler troubleshooting

S. 0No heat demand
S.1Fan running
S. 2Water pump running
S. 3Ignition sequence
S. 4Burner ignited
S. 5Fan and pump running
S. 6Fan over run
S. 7Pump over run
S. 8Anti cycling mode
S.10Hot water demand
S.11Fan running
S.13Ignition sequence
S.14Burner ignited
S.15Fan and pump running
S.16Fan over run
S.17Pump over run
S.20Warmstart demand
S.21Fan running
S.22Pump running
S.23Ignition sequence
S.24Burner ignited
S.25Fan and water pump running
S.26Fan over run
S.27Pump over run
S.28Anti cycling mode
S.30No heating demand from external controls (clamp 3-4 open)
S.31Central heating thermostat knob turned off or no heat demand by the eBUS control unit
S.32Heat exchanger antifreeze active, as fan speed variation is too high. Appliance is within the waiting time of the operation block function
S.34Antifrost mode active
S.36No heating demand from low voltage controls (clamp 7-8-9)
S.41Water pressure > 2,9 bar
S.42Response from accessory modul or defective condensate pump is blockinq burner operation
S.52Water pressure > 2,9 bar
S.53Appliance is within the waiting period of the operation block function due to water shortage (VL-RL spread too big)
S.54Appliance is within the waiting period of the operation block function due to water shortage (temperature gradient)
S.96Return-sensor check is running, demand (DHW or heatinq) is blocked
S.97Water pressure sensor check is running, demand (DHW or heatinq) is blocked
S.98Flow-/Return-sensor check is running, demand (DHW or heating) is blocked


Error codes and troubleshooting