Common Vaillant Boiler Problems and Solutions

April 25, 2023 | News

Common vaillant boiler problems

Vaillant boilers are well-regarded for their efficiency and durability. However, like all appliances, they can experience issues over time. In this comprehensive guide, we’ll explore common Vaillant boiler problems and their fixes, ensuring you’re equipped to handle any situation that may arise.

Common Vaillant Boiler Problems and Fixes

1. Low Water Pressure (F22 Error Code)

A common issue with Vaillant boilers is low water pressure, indicated by the F22 error code. To resolve this problem, locate the external filling loop and open it, raising the pressure back to 1.5 bar. If your boiler has a built-in filling loop, consult your manual for instructions.

Book a boiler quote

Call our specialists on 020 8395 8616 or fill in our booking form.

2. Faulty Pressure Sensor or Pump (F75 Error Code)

If your Vaillant ecoTEC boiler displays an F75 error code, there might be an issue with the pressure sensor or the pump. In this case, a qualified engineer will need to inspect the boiler and determine whether the pump or pressure sensor requires repair or replacement.

3. Ignition Failure (F28 and F29 Error Codes)

A failed ignition, which results in no hot water or heating, is another common problem with Vaillant boilers. If you see an F28 or F29 error code, the issue could be caused by a frozen condensate pipe, a lack of gas supply, or defective spark electrodes. A professional engineer will diagnose and resolve the problem accordingly.

4. Incorrect Flame Detection (F27 Error Code)

An F27 error code indicates that the boiler’s flame detection is faulty. This problem may result from moisture in the electrical components, worn ignition leads, or a malfunctioning printed circuit board (PCB). A qualified Gas Safe engineer will need to repair the issue.

5. Frozen Condensate Pipe

If your Vaillant boiler’s condensate pipe is frozen, it can cause multiple problems. You can fix this issue by thawing the pipe using warm water. If you’re not comfortable with this approach, contact a professional for assistance.

6. Slow Flow Rate

A slow water flow rate from taps and showerheads can be caused by a malfunctioning pump, incorrect water tank height, or an issue with an open-vent heating system. A professional engineer will need to diagnose the problem and provide a solution.

7. Faulty Gas Valve (F62 Error Code)

A stuck gas valve can create a dangerous situation by allowing the gas supply to continue flowing after the hot water or heating has been turned off. If you see an F62 error code, a Gas Safe engineer must attend to the issue.

8. Over Activity

Over activity in Vaillant ecoTEC Plus boilers could be due to a faulty thermostat or incorrect temperature settings. If the boiler is firing up unexpectedly, verify the temperature levels and time settings. If the problem persists, consult a professional.

9. Sensor Faults (F52 and F53 Error Codes)

F52 and F53 error codes indicate an issue with the mass flow sensor, located just behind the gas valve and connected to the fan in Vaillant ecoTEC boilers. A professional engineer will need to perform an electrical test and, if necessary, install a replacement.

10. Unstable Flame (F68 Error Code)

An unstable flame, indicated by an F68 error code, can be caused by several factors, including low gas flow pressure, a frozen condensate pipe, or air in the gas. A qualified engineer will need to address this issue.

When to Call a Professional Engineer

While some Vaillant boiler issues can be resolved without professional help, others require the expertise of a qualified Gas Safe engineer. If you encounter any of the following scenarios, it’s crucial to contact a professional for assistance:

  • Error codes that indicate a problem with internal components or the gas supply.
  • Any issues involving gas or electrical components.
  • When you are unsure about the nature of the problem or its solution.
  • If you suspect that there is a risk of gas leakage or a dangerous situation.

Regular Maintenance for Vaillant Boilers

To minimise the likelihood of encountering problems with your Vaillant boiler, it’s essential to schedule regular maintenance checks. This includes:

  • Annual servicing by a qualified Gas Safe engineer.
  • Regularly checking the boiler’s pressure and topping up as necessary.
  • Ensuring the boiler’s settings are adjusted correctly.
  • Inspecting the boiler for any signs of corrosion, leakage, or damage.
  • Cleaning the boiler’s condensate pipe and trap.

By following these guidelines, you can extend the lifespan of your Vaillant boiler and maintain its efficiency and safety.


Vaillant boilers are known for their reliability and energy efficiency. However, like any appliance, they can develop issues over time. By familiarising yourself with common problems and their solutions, you can ensure your boiler remains in good working order. Remember to schedule regular maintenance checks and seek professional help when needed to keep your Vaillant boiler running smoothly and safely.

Open chat
How can we help?