What does the Baxi 600 Series E790 fault code mean?
The E790 fault code on the Baxi 600 Series indicates a fault with the domestic hot water (DHW) thermostat. This issue can prevent the boiler from heating water properly, leading to inadequate hot water supply.
Common Causes
- Faulty DHW Thermostat: The thermostat may be malfunctioning or damaged, causing incorrect temperature readings.
- Wiring Issues: Damaged or loose wiring connections to the thermostat can disrupt its functionality.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as it involves gas and electrical components. Attempting to fix it yourself could be dangerous.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for replacing the DHW thermostat is around £150 to £200. This includes parts and labour, as the thermostat itself typically costs between £50 and £100, with the remainder covering the engineer’s time.