BoilerFaultCodesTechnical description
Appliance stays fired after time clock/programmer has switched off: External wiring fault or Faulty motorised valve
What causes this fault?
This fault occurs when a component in your external heating system fails to send the 'off' signal to the boiler, or the signal is ignored. The most common reason is a motorised valve that has physically jammed in the open position or has an electrical defect that keeps the boiler's firing circuit active even after the timer has switched off.
This issue is more frequently noticed in autumn when heating systems are turned back on after a summer of inactivity, which often causes moving parts like motorised valves to seize.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.