L7
FAULT CODE
Ideal
DHW Thermistor Lockout
High Severity
Engineer Required
The domestic hot water temperature sensor has caused a lockout — either due to a sensor failure or genuinely dangerous DHW temperatures.
Step-by-Step Fix Guide
-
Step 1
Turn off the boiler
-
Step 2 Engineer only
Call a Gas Safe engineer to inspect the DHW thermistor
Gas Safe Reminder
Work on gas appliances must be carried out by a Gas Safe registered engineer. The steps above cover safe checks a homeowner can perform - any internal component replacement requires a qualified professional. If in doubt, always call an engineer.