• if your appliance has a pilot light and it has gone out, there are usually instructions on how to re-light it on the front of the boiler or inside the boiler door (pilot lights tend to be in boilers over 18 years old). Or consult your instruction manual.
  • 1. A slight draft could cause excess air to get into your gas supply and cause your pilot light to blow out or burn yellow or orange. This is one of the most common reasons for a pilot light to burn yellow, and can be resolved by simply draught-proofing your property and ensuring the boiler cover is properly secured.
  • 2. Make sure you do not block any vents or flues, don’t unscrew or remove the boiler cover or attempt to interfere with any internal mechanisms of the boiler if you are not Gas Safe-registered.
  • 3. If your pilot light is yellow, or even if has a slight yellow or orange tint or is more elongated than normal you should arrange for a gas-safe engineer to inspect your appliance as soon as possible as it could be a sign of a carbon monoxide.
  • 4. If you have misplaced or lost your user manual, you can locate a replacement manual from this list of Vaillant boilers (please have your model number to hand).
  • We update the maintenance tips and troubleshooting guidance from time to time and aim to make it as helpful as possible. The purpose of the maintenance and troubleshooting section of this website is to provide you with general guidance. Please ensure you read and follow our instructions carefully and do not undertake the maintenance or troubleshooting unless you are aged 18 or over, are competent to do so and are confident that you can complete the maintenance. If in doubt do not attempt any actions and where an appliance is gas fuelled refer to a Gas Safe engineer for assistance.

    This website is not intended to be a substitute for professional advice and does not:
    - cover every reason that your product could fail;
    - cover all of the maintenance that can be undertaken for your product;
    - supersede any advice in your instruction manual or from your product manufacturer.

    Do not carry out any maintenance or use the troubleshooting guide if it puts you or anyone else in danger or if you believe it may cause damage to your, or another person’s property.