What does the Viessmann Vitodens 050-W E389 fault code mean?
The E389 fault code indicates a problem with the system supply sensor, which is responsible for monitoring the temperature of the water circulating through the heating system. This fault can lead to inefficient heating and may cause the boiler to shut down to prevent damage.
Common Causes
- Faulty Sensor: The supply sensor may be defective or damaged, leading to incorrect temperature readings.
- Wiring Issues: Damaged or loose wiring connections to the sensor can disrupt its functionality and cause the fault code to appear.
Can I fix it myself? (DIY)
It is advisable to call a Gas Safe Engineer to diagnose and repair this issue, as it involves electrical components and safety risks associated with gas appliances.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for replacing the supply sensor is around £150 to £250, which includes the cost of the part and labour. This estimate is based on typical service rates and the price of Viessmann replacement parts.