What does the Vaillant ecoTEC plus F43 fault code mean?
The F43 fault code on a Vaillant ecoTEC plus boiler indicates a malfunction with the flow sensor, which is responsible for measuring the flow of water through the system. This issue can lead to improper heating and may prevent the boiler from operating efficiently.
Common Causes
- Blocked Flow Sensor: Debris or limescale buildup can obstruct the flow sensor, causing it to malfunction.
- Electrical Fault: Issues with the wiring or connections to the flow sensor can lead to incorrect readings and trigger the fault code.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer to address this issue, as it involves electrical components and potential gas safety risks. Attempting to fix it yourself could void your warranty or lead to further complications.
Estimated Repair Cost (2026 UK Prices)
The estimated cost to repair the flow sensor issue is around £150 to £250, which includes the price of the replacement part and labour. This cost reflects the complexity of diagnosing and replacing the sensor by a qualified technician.