BoilerFaultCodesTechnical description
waiting time: temperature difference flow - return sensor too high (Check thermistor fit)
What causes this fault?
This fault occurs when the boiler detects that heat isn't being moved away from the unit quickly enough, causing the outgoing water to become significantly hotter than the returning water. The most common reasons are a failing internal pump that can't push the water around your radiators, or a buildup of sludge and debris that is restricting the flow within the system.
This issue often surfaces in autumn when the heating is turned back on for the first time, as pump components can seize or debris can settle during the summer months.
DIY fix possible
Check that all radiator valves are fully openEnsure the boiler pressure is between 1.0 and 1.5 barBleed your radiators to remove any trapped air