Worcester Bosch E9 219 fault code: heating safety overheat

What Does Error E9 219 Mean?

Worcester Bosch assigns E9 with cause code 219 to the central heating safety temperature limiter having tripped, meaning the flow temperature at the heat exchanger climbed past its allowed limit. It points at heat not moving away from the exchanger fast enough, from a circulation, pump, or fouling problem, rather than at a single failed part. Applies to: Worcester Bosch Greenstar boilers that pair E9 with cause code 219 This reading follows Worcester Bosch Greenstar literature that displays a fault code alongside a cause code and lists 219 as the safety temperature limiter. Other Worcester ranges and other E9 cause codes can differ, so record both numbers together before acting. Owner-safe checks: Note both numbers, E9 and 219, and the time the lockout appeared, then leave the boiler switched off rather than cycling the reset. | Check that any labelled isolation valves under the boiler are open and in the same position as normal, without removing covers. Qualified technician: Pump, flow sensor, heat exchanger, safety limiter, and system flushing work all require a Gas Safe registered engineer, and the boiler should stay off until then.