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Worcester Bosch Fault, Error Codes & Boiler Problems

Should a fault develop with your boiler (or the system), your boiler will enter a safety lock-out mode, and fault code information will be generated as described below.

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Locking error The boiler display will flash a warning triangle and fault code. At the same time a (static) cause code will also be displayed. Manual intervention (Pressing the reset button on the boiler fascia) is required following clearance of the fault.
Blocking error The boiler will stop operating with no fault data displayed. The cause code, in the info menu, is accessed by pressing the spanner/return button. The condition will clear automatically when the associated fault clears e.g. waiting for an area to cool. In some cases a blocking error has a defined time duration prior to changing to a locking condition.
Fault error Alpha numeric code indicating the fault group
Cause error Three digit number. During a blocking error (or normal operating status) it is not displayed, but accessed in the info menu via the spanner/return button. During a locking error the cause code flashes on the display.
Maintenance codes

These are displayed with the letter H followed by a number. The code advises of a situation that will need some attention but is not a fault that will stop the boiler from functioning. Some of the common ones are listed:

H11
Hot water outlet sensor defect, hot water can still be delivered but with less control

H13
A time has been set in the Service interval function i.e. 1 to 72 months and that time has expired. Menu 2.5F allows this feature to be set (1 to 72), a 0 will disable this function.

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Locking Errors

Fault codes Cause codes Description Reset type Possible Cause
9A 362 HCM (Heat Control Module) Reset button Incorrect HCM fitted
9U 233 HCM (Heat Control Module) Reset button Problem with the code plug (faulty or not connected)
b7 257 Internal error Replace control board
C6 215 Fan problem Reset button Running too fast
C6 216 Fan problem Reset button Running too slow
C7 214 Fan problem Reset button Fan not running
C7 217 No airflow after a defined period of time Reset button Fan not running or airflow blocked
D1 240 Return sensor error Reset button Sensor wet or damaged (the boiler will block for 300 seconds before this condition)
D1 241 Return sensor error Reset button Sensor disconnected or damaged (the boiler will block for 300 seconds before this condition)
D1 286 Return temperature too high Reset button Boiler overheat
E2 222 Flow sensor short circuit Reset button Flow sensor shorted or damaged
E2 223 Flow sensor open circuit Reset button Flow sensor disconnected or damaged
E5 218 Flow temperature too high Reset button Primary flow sensor overheated
E5 332 Primary flow sensor has exceeded 110°C Reset button Primary flow sensor overheated
E9 219 Safety sensor temperature too high Reset button The main heat exchanger has overheated.
Maximum temperature 105°C
E9 220 Safety sensor short circuit Reset button Maximum temperature sensor on the main heat exchanger has failed
E9 221 Safety sensor open circuit Reset button Maximum temperature sensor on the main heat exchanger has not been recognised
E9 224 Max temperature thermostat activated Reset button Flue gas thermostat overheat
EA 227 No flame detected after ignition Reset button Failure of four ignition attempts. The boiler waits 30 seconds before another attempt is made
EA 229 Loss of flame signal during operation Reset button

An established flame has been extinguished.

This could be caused by:

  • moisture in the sump, due to a blocked sump/condensate trap.
  • a strong wind into the flue
EA 234 Gas valve error Reset button Gas valve coil disconnected
EA 261 Ignition timing error Reset button Flame not established during the first 4 seconds ignition period
EA 338 Too many short burner starts without confirmation Reset button There is an error where the pump is not detecting water - check pressure gauge and repressurise to 1 bar.

Blocking Errors

Fault codes Cause codes Description Possible Cause
A1 281 Pump stuck or running in air Little or no water in the system - check pressure gauge and repressurise to 1 bar.
C1 264 Airflow stopped during operation Fan has stopped
EA 227 No ionisation detected after ignition No flame is detected. The boiler will block during 4 attempts before going to Locking fault
EF 349 Central heating, boil detect.
Large delta T despite minimum burner
The boiler is operating at minimum burner load and there is a greater than 18°C Flow & Return temperature difference
No code 212 Safety or flow temperature rises too fast Air lock or reduced water content - check pressure gauge and repressurise to 1 bar
No code 213 Temperature difference between supply and return exceeding limit Air lock or reduced water content - check pressure gauge and repressurise to 1 bar.
No code 260 No temperature rise after burner starts Sensor disconnected or no water content - check pressure gauge and repressurise to 1 bar

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[28] Exclusions apply. See www.help-link.co.uk/fixed-price-quote-faqs/

[79] Online discount is available to domestic gas and LPG customers who receive an online quote for all boiler brands excluding Vokera. Discount will be applied as long as the quoted price is still applicable at the point of sale. Online discounted price is only available for the duration of the 14-day quote validity which starts from the day the quote was given. Offer is not available to Help-Link UK Ltd employees.

Online discount can be applied as follows:
All boiler manufacturer types excluding Vokera are eligible for a 5% discount off the final quoted price. Conventional to combi boiler swaps also qualify for an additional £50 discount after 5% initial discount is applied.

This offer cannot be used in conjunction with any other offers.
Offer available from April 2017. Any boiler quotations before this date will not be eligible for the discount post purchase. Help-Link UK Ltd have the right to withdraw or change the offer at any time.
Online discount is automatically applied when the customer gets a quote using the online quote system at www.help-link.co.uk and as long as the customer meets all the above criteria.