You may have asked for information on a Vaillant fault code. Please take a look at the boiler fault codes below. Don’t worry if you have one of these, it doesn’t necessarily mean your boiler is broken. Your boiler may just need resetting or you have an issue that is easily resolved.
Below we have the fault codes for the ecoTEC Plus series of boilers. You may have different fault codes as they differ across Vaillant boiler models.
Short circuit: Cylinder sensor: Combination product: Warm start sensor/cylinder sensor short circuitCombination product with actoSTOR: Short circuit cylinder sensor (NTC) only in combination with F.91NTC defective, short circuit in cable harness, cable/casing
Safety switch-off: Temperature limiter: 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
Fault: Fuel valve not working: Gas valve stepper motor not connected, multiple plug on the PCB not plugged in correctly, interruption in cable harness, gas valve stepper motor defective, electronics defective
Start-up failure: Ignite unsuccessful: Gas meter defective or gas pressure monitor has triggered, air in gas, gas flow pressure too low, thermal isolator device (TAE) has triggered, condensate duct blocked, incorrect gas restrictor, incorrect spare part gas valve, value in D.052 does not correspond to the printed value on the current gas valve, fault on the gas valve, multiple plug on PCB incorrectly plugged in, break in cable harness, ignition system (ignition transformer, ignition cable, ignition plug, ignition electrode) defective, ionisation current interrupted (cable, electrode), incorrect earthing of product, electronics defective
Contact fault mass flow sensor/Venturi: The mass flow sensor/Venturi is not connected electrically – The plug is not plugged in correctly – The plug is not plugged in – The plug is defective – The slot is defective (loose connection) – Mass flow sensor/Venturi defective
Combustion regulation fault: The combustion regulation has detected a fault – Gas flow pressure too low – Liquid gas coding resistance used when operating with natural gas – If the fault occurs again after being cleared: – Gas valve defective – Mass flow sensor/Venturi defective, wet or blocked (if the fault occurs again after being cleared): Do not wet the sensor, do not use any lubricants on the O-ring on the Venturi.
Safety switch-off: CO limit exceeded: Safety switch-off: CO limit exceededA component in the combustion regulation is defective– Contact fault at the gas valve (plug not plugged in correctly or not plugged in, plug defective, slot is defective (loose connection))– If the fault occurs again after being cleared: The gas valve is defective
Fault: Fuel valve switch-off delay: Delayed shutdown of gas valve detected– Secondary light (ignition and monitoring electrode indicates delayed extinguishing of the flame signal)– Gas valve defective– PCB defective
Fault: Flame signal unstable: Air in gas, gas flow pressure too low, incorrect air ratio, condensate duct blocked, ionisation flow interruption (cable, electrode), flue gas recirculation, condensate duct