What does the Viessmann Vitodens 200-W F40 fault code mean?
The F40 fault code indicates a problem with the combustion air sensor, which is responsible for monitoring the air supply necessary for efficient combustion. This fault can lead to improper combustion and may affect the boiler’s performance and safety.
Common Causes
- Blocked Air Intake: Debris or obstructions in the air intake can prevent adequate airflow, causing the sensor to malfunction.
- Faulty Sensor: The combustion air sensor itself may be defective or damaged, leading to incorrect readings and triggering the fault code.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for any issues related to gas appliances, including the combustion air sensor. Attempting to fix it yourself can be dangerous and may void your warranty.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for replacing a faulty combustion air sensor on a Viessmann Vitodens 200-W is approximately £150 to £250. This includes the cost of the part and labour, reflecting the complexity of the repair and the need for a qualified technician.