FAULT CODES

None

Fault Code Reference - Model 4740648

Status	Description	Additional Information
H11	DHW sensor short or open circuit	Given no other faults, boiler will still operate using the primary flow and return sensors to modulate the DHW
H13	Service Due
200	CH system is being heated	Boiler has ignited, established and is running for a central heating demand
201	DHW system is being heated	Boiler has ignited, established and is running for a hot water or preheat demand
202	Anti rapid cycle mode	Central heating demand removed and then reinstated within the anti-cycle time set in 2.3B (default 10 minutes)
203	System stand by	Boiler has completed its self check and currently has no demand for heating, preheat or hot water
204	System waiting, primary flow temperature above setpoint	System is running for heating or hot water but primary flow sensor above 80°c for DHW or above the temperature setting for CH
205	Waiting for airflow
207	System pressure too low
208	Test mode active due chimney switch	Service mode activated (either on maximum or minimum)
210	Flue stat activated	Flue overheat thermostat has gone open circuit
211	TTB opened (thermal kickback device)
212	Safety or flow temperature rises too fast	Safety or flow sensor has measured water temperature increase of over 5°C a second
213	Temperature difference between supply and return exceeding limit
214	Fan not running	Signal from fan hall sensor not being sent or received
215	Fan running too fast
216	Fan running too slow
217	No Airflow after defined period of time
218	Flow temperature too high	Flow sensor reading above 110°C
219	Safety sensor temperature too high	Safety sensor reading above 110°C
220	Safety sensor shorted	Safety sensor short circuit or very low resistance
221	Safety sensor disconnected	Safety sensor open circuit or very high resistance
222	Flow sensor shorted	Flow sensor short or very low resistance
223	Flow sensor disconnected	Flow sensor open circuit or very high resistance
224	MAX thermostat activated
225	Difference between flow and safety exceeding limit (bi-sensor only)
227	No ionisation detected after ignition	Burner not igniting or igniting and not rectifying
228	Ionisation current detected before burner-start
229	Loss of ionisation signal during operation	Burner cutting out or losing rectification during demand
230	Ionisation signal out of bounds
231	Mains power error - electrical power interruption	Mains power turned off to appliance whilst in lockout
232	external cut-off switch activated
233	HCM problem	Code plug missing or faulty
234	Gas valve coil disconnected	One or both gas valve solenoids high resistance or open circuit
237	Airflow present during last 24 hours - fan running continuously
238	Gas valve error	Gas valve shorting to earth or gas valve solenoid went open circuit / high resistance whilst appliance lit
239	Watchdog relay error
240	Return sensor shorted
241	Return sensor disconnected
242	Internal error
243	Internal error
244	Internal error
245	Internal error
246	Internal error
247	Internal error
248	Internal error
249	Internal error
250	Internal error
251	Internal error
252	Internal error
253	Internal error
254	Internal error
255	Internal error
256	Internal error
257	Internal error - replace control board
258	Internal error
258	Low mains power supply	Incoming voltage below 170V AC
259	Internal error
260	No temperature rise after burner start	Burner has ignited and rectified but flow temperature has not increased
261	First safety timing error
262	Internal error
263	Internal error
264	Airflow stopped during operation
265	Stand-by mode forced due to energy transfer limit
266	No pressure variation detected after switching pump
267	Watchdog timeout error
268	Component test mode	Shown whilst test t1-t6 is active
269	Ignition device activated too long
270	Power up mode	Shown whilst appliance is completing its self check
271	Temperature difference between flow and safety sensor exceeding limit	Temperature difference between the flow and safety sensor whilst boiler was lit is greater than 15°C
272	Internal error
273	Airflow present during last 24 hours
274	Ionisation signal present during last 24 hours
276	Flow temperature exceeded 95°C
277	Safety sensor temperature exceeded 95°C
278	Sensor test failed
279	AD converter error, unstable measurement
280	Recycle timing error
281	Pump stuck or running in air
282	No feedback from pump
283	Burner starting	Shown as boiler is beginning sparking stage of ignition sequence
284	Gas valve(s) opened, first safety time started	Shown during the ignition sequence, appliance is now sending voltage to the gas valve
285	Return temperature exceeded 95°c	This will not go to a lockout condition unless the temperature remains over 95°c for 5 minutes or longer
286	Return temperature too high	This will not go to a lockout condition unless the temperature remains over 95°c for 5 minutes or longer
287	Ionisation sensor shorted
288	Water pressure sensor not connected or short-circuit to supply
289	Water pressure sensor not connected or short-circuit to ground
290	AD converter reference error
305	Anti fast cycle mode	Short anti purge mode after a DHW demand has ended
306	Ionisation detected after burner stop	Flame detected after demand ended
307	Pump stuck
308	Pump running in air
309	CH & DHW system are being heated
310	CUS communication error
311	CUS locked
312	CUS blocked
313	CUS reported error condition
314	Mains disconnected during super lockout	Mains power turned off while appliance was in status 373 or 374
315	Several times lack of water flow
316	Flue gas sensor temperature too high
317	Flue gas sensor shorted
318	Flue gas sensor disconnected
321	Self-test of flue gas supervision
322	Code error
323	EMS communication error
324	DHW-NTC defect	DHW sensor resistance not stable
325	DHW-NTC not correctly installed
326	Storage-NTC defect
327	Reset-key stuck or short-circuit
328	Internal error
329	No pressure variation detected after switching pump
332	Supply sensor exceeded 110°C	Flow sensor greater than 110°C
333	Start temporarily not allowed due to flow error on CH	Flow sensor resistance not stable
338	Too many short burner starts without confirmation of water flow
341	CH: supply and/or return temperatures rising too fast	Whilst appliance is lit it has detected flow or return sensor temperature increasing by 5°c a second or more
342	HW: supply temperature rising too fast	Whilst appliance is lit it has detected flow sensor temperature increasing by 5°c a second or more
343	CH: flue gas temperature rising but supply temperature not
344	HW: flue gas temperature rising but supply temperature not
345	Supply and/or return temperatures do not change after burner start
346	Flue gas temperature rising too fast
347	Return temperature higher than supply temperature (some time after burner start)
348	HW: supply temperature too hot
349	CH: Boil Detect, large delta T despite minimum burner load	The boiler is operating at minimum burner load and the temperature difference between the flow and return sensors is greater than 18°C
350	Flow sensor shorted
351	Flow sensor disconnected
353	Burn temporarily blocked due to no 20 minute continuous OFF time in last 24 hours
354	Overpressure setting erased
356	Low mains power supply	Incoming voltage below 170V AC
357	Primary Heat Exchanger air venting program active - approx. 100 seconds	Setting 2.2C in parameters set to 1 in last 100 seconds
358	Three way valve kick	Displayed briefly as diverter valve changes position
359	DHW outlet temperature too hot
360	HCM problem	Incorrect code plug fitted or code plug faulty. Also displays if PCB has been fitted to a different appliance previously.
364	Gas valve EV2 leak test failed
365	Gas valve EV1 leak test failed
372	Temporarily ignoring CH requests to limit temperatures of the appliance components
373	SuperLock caused by too frequent thermostat overheat detections during burning
374	SuperLock caused by too frequent ionisation loss during burning
375	Preheat sensor on DHW inlet Short Circuit	Resistance of preheat sensor short circuit or very low resistance
376	Preheat sensor on DHW Inlet Open Circuit	As this sensor is optional this will only display if the sensor resistance was not open circuit during the appliance self check but has then gone open circuit or very high resistance
380	Inlet temperature greater than DHW Outlet Set point
800	Outdoor sensor defect
808	Domestic hot water sensor defect
810	Domestic hot water remains cold
828	Water pressure sensor defect

For example type "EA" or "227" into the box