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Worcester Boiler Fault Codes and Errors
Contents
- 1 What are Worcester Boiler fault codes?
- 2 Worcester Bosch Greenstar heat slave II Oil boiler fault codes
- 3 Worcester Bosch Greenstar CDI Classic regular boiler error codes/ Greenstar CDI Fi Regular error codes.
- 4 Worcester Greenstar I Combi and system boiler error codes
- 5 Worcester CDI Classic Combi boiler Error codes
- 6 Greenstar I system 27/30, Greenstar I system 25/30 and Greenstar CDI Compact error codes
- 7 Greenstar CDI Highflow error codes
- 8 Greenstar 8000 error codes
- 9 Greenstar Ri boiler error codes.
Worcester Bosch is a leading boiler brand with massive acceptance ratings. However, like many things, the Worcester boiler is a victim of poor maintenance and time. The latter is inevitable; however, proper care can keep your Worcester Bosch in excellent condition, even lengthen its life span. In the unfortunate circumstance of malfunctioning, Worcester will initiate a lockout procedure.
The shutdown procedure prevents further damage from the initial problem. Fortunately, your Worcester boiler will also display error codes that will unravel the specific situation for your Gas Safe engineer to sort out. The manual that comes with the boiler has a list of all the error codes. But man is to err, so we have listed all the error codes you can infer if you lose it.
If you notice an error code displayed, try resetting your boiler; if it does not work, you are better of calling a qualified gas engineer. Tempering with the inner parts of your boiler could fester the problem.
What are Worcester Boiler fault codes?
Worcester boiler error codes are alphanumerical codes that pop up on display in the case of a problem. The codes generally identify specific faults and ways of fixing them and are particularly useful to the Gas Safe registered engineer. The error shows them how best to handle the situation.
The error codes are divided into; blocking errors, fault errors, locking errors, cause errors and maintenance codes. Worcester Bosch has an extended range of models, and the fault codes vary in different models.
Types of Worcester Bosch error codes
- Blocking errors – When a blocking error occurs, the Worcester boiler goes into a shutdown procedure immediately. However, unlike other errors, no error codes will be displayed. Instead, pressing the spanner or the return button will reveal the cause of the blockage, and the boiler will start generally operating once the problem is solved.
- Locking errors – In case of a locking error, the boiler will display the error code, cause code and flash a warning triangle. After fixing the boiler, you will need to press the reset button for three seconds to clear the error.
- Fault errors – Fault errors indicate the fault group. They are alphanumeric codes that appear on your boiler.
- Cause errors – These are three-digit numbers that usually flashes on the display panel during a locking error. They never display during a blocking mistake or normal operating status. You can access them in the info menu via the spanner or the return button.
- Maintenance codes – The maintenance codes are easily distinguishable. They start with an ‘H’ followed by a number. Luckily, maintenance codes do not initiate a lockout, but they act as a warning and require a check-up from a qualified gas engineer.
How to reset a Worcester boiler
Resetting the boiler can clear a few error codes that will not require you to contact a qualified gas engineer. We advise you to always resort to resetting your boiler before getting a Safe Gas registered engineer unless the boiler is displaying an EA error code. If your boiler fails to operate, calling a qualified gas engineer is the best course.
There are two ways of resetting a Worcester Bosch boiler depending on its boiler. Other models will have a clear ‘reset’ button that you press down for three seconds, while others will have a light at the end of the temperature dial, which you turn down until you reach the ‘reset’ point and then hold it there for three seconds.
Worcester Bosch Greenstar heat slave II Oil boiler fault codes
| Fault code/ Cause code | Description | Possible causes/ solutions |
| E9 210 | The maximum temperature thermostat or air pressure switch is activated. | The flue gas or tank thermostat has over-heat. Reset the overheated thermostat or air pressure switch, then reset your boiler. |
| 212 | The safety or flow temperature is too high. | The cause of the high temperature is an airlock or reduced water content. |
| E5 218 | The flow temperature is too high. | The primary sensor is overheated. Reset after 30 minutes. |
| E9 219,220 and 221 | Safety temperature too high. | The primary heat exchanger has overheated. Wait 30 minutes and rest. |
| E2 222, 223 | The flow sensor has a short circuit | The flow sensor open circuit or the plug for the heat control module code is missing or defective. |
| E2 233 | Heat Control Module (HCM). | HCM Code plug missing or defective. |
| F0 237, 238 | Software relay error. | Resistors between plus X4 pins 3 and 5 disconnected or water in the burner control box. |
| F0 239, 259 | A/D reference relay error. | If the error persists, have a qualified engineer change the control board. |
| F0 263 | Appliance powered off with locking fault present. | Press the reset button to clear. |
| D4 271 | The difference between flow and safety sensors temperature exceeds the limit. | Check the flow sensor is seated correctly on the flow pipe, and the primary heat exchanger should be at 15 degrees Celsius. |
| E9 276,277 | Safety and flow temperatures exceed 95 degrees Celsius. | Wait for the boiler to cool and reset after 30 minutes. |
| F0 278,279 and 290 | There is a sensor test error, A/D convertor error or A/D convertor reference error. | If the error persists, have a qualified engineer change the control board. |
| E5 332 | Primary flow has exceeded 105 degrees Celsius. | The primary sensor is overheated. |
| 359 | DHW outlet or storage tank exceeds 90 degrees Celsius. | The pump and burner are blocked till the temperature falls below 90 degrees Celsius. Wait 30 minutes for temperatures to drop. |
| 9A 360 | Incorrect HCM for boiler variant. | Replace with correct HCM. |
| 380 | The inlet DCW temperature is higher than the DHW outlet temperature. | Wait for 30 minutes before resetting. |
| A7 808 | DHW sensor is defective. | Check and replace the defect sensor as necessary. |
| A0 809 | Thermal store sensor defective | check and replace defect sensor as necessary |
| 9F 855,856 | Burner lockout or five-burner lockouts resets intermittently. | Ensure the burner and the oil supply is free of contaminants. After several lockouts, code 856 pops up on display. |
| H29 | Warning triangle on the controller. | It indicates the weather compensation is active, but no weather sensor detected. |
| H27 | A warning triangle symbol on the controller. | DCW in sensor defect. |
Worcester Bosch Greenstar CDI Classic regular boiler error codes/ Greenstar CDI Fi Regular error codes.
| Fault Code | Possible cause/ How to fix it |
| B1 | A code plug is not detected. |
| C6 | Fan speed is too low. Check the fan harness and connector. |
| E2 | Central heating (CH) flow and the (NTC) sensor are defective. |
| E9 | The safety temperature limiter in CH flow has tripped. |
| EA | The flame is not detected. Contact a qualified heating engineer. |
| F0 | Internal error. |
| F7 | Flame detected even though the appliance is off. |
| FA | Flame detected after the gas is off. |
| FD | Someone pressed the reset button by mistake. |
Worcester Greenstar I Combi and system boiler error codes
| Fault Code | Possible cause/ How to fix it |
| 226 | There is a connection of the service tool to the blocking error history menu. |
| FD 231 | Power interruption during a lockout. |
| C7 214 | The fan fails to run during the start-up phase. The fan harness connector needs checking. |
| C6 215 | Fan speed is too high. Contact a qualified heating engineer. |
| C7 216 | Fan speed is too low. Have a registered engineer check your fan. |
| C7 217 | The fan has stopped during appliance operation. |
| C1 264 | The fan is not working during an operation. |
| C4 273 | The fan has been running continuously for the last 24hours, and the appliance is temporarily blocked. |
| E2 222 | Flow temperature sensor shorted. |
| E2 233 | Flow temperature sensor disconnected. |
| E9 276 | Primary flow temperature exceeded 95 degrees Celsius. |
| E2 350 | Flow temperature sensor shorted. |
| E2 351 | Flow temperature sensor disconnected. |
| FA 306 | Ionisation takes place after the gas valve is closed. |
| EA 227 | No ionisation after ignition. |
| F7 228 | Ionisation current detected before burner start. |
| EA 229 | No ionisation signal during operation. |
| EA 261 | The heat control module (HCM) is potentially defective. |
| 9U 233 | The control is defective or loose, and the HCM needs attention. |
| C4 237 | The control box is defective. |
| F0 238 | Gas valve error or control box error. Check the gas valve coils. |
| F0 239 | The control box is defective. Check the control box connections. |
| F0 242 | The control box is defective. Check the HCM and control box connections. |
| B7 257 | The control box is defective. Check HCM or control box connections. |
| F0 258 | The control box is defective. Check HCM or control box connections. |
| EH 258 | The control box is defective. Check HCM or control box connections. |
| F1 259 | The control box is defective. Check HCM or control box connections.
|
| F0 262 | The control box is defective. Check HCM or control box connections. |
| F1 263 | The control box is defective. Check HCM or control box connections. |
| F0 272 | The control box is defective. Links need checking, or HCM is not inserted correctly and needs replacing. |
| F0 280 | The control box is faulty. Connections need checking, or HCM is not inserted correctly and needs replacing. |
| F0 290 | The control box is defective. Check HCM for incorrect insertion, or it may need replacing. |
| 328 | Internal error with the mains voltage. The frequency may be inconsistent. |
| 235 | Incompatible software versions of HCM. The control box needs the latest software. |
| 356 | Low mains voltage. Check for inconsistent and interruptive voltage. |
| 360 | Heat control module (HCM) invalid. HCM does not correlate with the control box. |
| A8 362 | Low mains voltage. Check for unstable and interruptive voltage. |
| CC 800 | Outdoor sensor defect is available when the outdoor accessory sensor is connected. |
| A1 281 | Pump stock or running dry. |
| E9 224 | Flue or high limit thermostat activated. |
| D4 341 | Primary flow temperature rising too fast. |
Worcester CDI Classic Combi boiler Error codes
| Fault Description | Possible cause/ How to fix it |
| A1 | The pump needs replacing or freeing as it is running dry or water is leaking. |
| A7 | The NTC sensor is defective. Check the hot water sensor or connecting leads. |
| A8 | Check the break communication to FX sensor controls electrical connections. |
| B1 | A code plug is not connected. |
| C6 | Fan speed is too low. The fan lead and connector may need replacing. |
| E2 | Central heating (CH) water flows and NTC sensor are defective. Check the central heating flow, Negative thermistor coefficient (NTC) sensor. |
| E9 | The safety temperature limiter in CH flow has tripped the system pressure. It needs checking by a heating engineer. |
| EA | No flame observation. Check the gas supply, power supply or igniter, electrode and lead. Contact a heating engineer. |
| F0 | Internal error. The electrical connector contacts or programmer interface module. Confirm the ignition leads are well fitted. |
| F7 | Presence of flame even though the appliance is off. Ensure that the electrode assembly is dry and the flue is not clogged. |
| FA | The presence of flame after turning the gas off. The gas valve needs checking. Contact a heating engineer. |
| FD | The reset button was pressed by mistake. Press the reset button again. |
Greenstar I system 27/30, Greenstar I system 25/30 and Greenstar CDI Compact error codes
| Fault Code | Possible cause/ How to fix it |
| T1 | Ignition test. Check the igniter spark. |
| T2 | Fan test. Check the basic fan |
| T3 | Pump test. Check the basic pump |
| T4 | Three-way valve test |
| T6 | Ionisation oscillator test |
| 9A 362 | Error. Incorrect HCM fitted. |
| 9U 233 | Heat Control Module (HCM) error. Indicates an issue with the code plug. |
| B7 257 | Internal error. Means a possible PCB problem. |
| C6 215 | Fan problem. The fan is running too fast and should be checked by a qualified heating engineer. |
| C7 214 | Fan problem. The fan is not running. |
| D1 240 | Return sensor error. The sensors might be wet or damaged. |
| E2 222 | Flow sensor short circuit error. |
| E5 218 | Flow temperature too high. |
| E9 219 | Safety sensor fault. The temperature is too high; the sensor has a short circuit or open circuit that needs checking. |
| EA 227 | No flame or flame signal loss during operation. |
| F0 237 | Internal error |
| F7 228 | Flame error. False flame or flame observed before burner started. |
| FA 306 | False flame fault. The flame was detected after the burner stopped. |
| FD 231 | Mains power fault. This means there is an electrical power interruption. |
| FA 364 | Gas valve EV2 leak test failed. This means the gas valve is leaking. |
| FB 365 | Failure of gas valve EV1 leak test |
| A1 281 | The presence of air in the system or pump is stuck. |
| C1 264 | Airflow stopped during the operation. |
| C4 273 | Airflow present during last 24 hours |
| D1 240 | Return sensor short circuit |
| D4 271 | The temperature difference between the flow and safety sensor surpasses the limitation. |
| E9 224 | Activation of the max thermostat – flue gas thermostat overheat. |
| EA 227 | No ionisation after ignition. |
| EF 349 | Central heating boil detected
Boiler operating at the minimum burner load with temperature difference more significant than 18 degrees Celsius between Flow and Return. |
| NO CODE 212 | Safety or flow temperature rising too fast. |
Greenstar CDI Highflow error codes
| Fault Code | Possible cause/ How to fix it |
| A1 | The pump is dry or running with air in the system. Check and adjust the pressure in the system. |
| A5 | Tank negative thermistor coefficient (NTC) is defective |
| A7 | Domestic hot water (DHW) or negative thermistor coefficient (NTC) is defective. |
| A8 | Energy Management System (EMS) communication error |
| B1 | The code plug is not detected |
| B2, B3, B4, B5, B6 | Data error |
| B7 | Burner control error |
| C6 | Fan defect |
| D3 | External temperature limiter |
| D5 | Condensate pump failure |
| D6 | Internal heat bank overflow |
| EA | Flame is not detected. You should contact a Safe Gas registered engineer. |
| E2 | The primary negative thermistor coefficient (NTC) is defective |
| E9 | The safety temperature limiter in central heating flow is malfunctioning |
| F0 | Detection of an internal fault. |
| F1 | ROM error. |
| F7 | Flame observed after the appliance is off. |
| FA | Flame noticed after gas shut off |
| FD | Reset button pressed. Try pressing the reset button again. |
Greenstar 8000 error codes
| Fault Code | Possible cause/ How to fix it |
| 200 O | Boiler in heating mode |
| 201 O | Boiler in hot water mode |
| 202 O | Boiler in anti-cycle mode |
| 203 O | Boiler on standby. |
| 204 O | The current primary water temperature is above the set value. |
| 208 O | Chimney sweep demand |
| 224 V | The safety temperature limiter has tripped. Top up the water in your boiler until you reach the recommended pressure. |
| 227 V | No flame signal after ignition. Your burner control unit may need a replacement. |
| 228 V | Flame signal without a flame present. This is an indication that the air/gas ratio control valve or ionisation cable may need replacing |
| 305 O | Boiler in hot water anti-cycle mode |
| 306 V | Flame signal after shutting the fuel supply off. Another indication is that the air/gas ratio control valve may need replacing. |
| 360 V | Incompatible code plug. Check that the correct code plug is installed and exchange or reconnect the code plug. |
| 815 W/B | Low loss header temperature sensor faulty. Check the differential sensor or the sensor port for the wrong installation. |
| 1010 O | EMS-Bus is damaged or not connected, or there is no Bus communication. To fix it, replace the damaged cable exchange fuse or connect the cable for the EMS-Bus.
|
| 1017 W | Water pressure too low. Check the boiler vent system and top up the water. |
| 1021 B | The hot water temperature sensor is defective. The sensor plug may not be connected or needs replacing. |
| 1022 B | The hot water storage temperature sensor is defective. Correctly connect the plug to the hot water temperature sensor or replace it. |
| 1037 W | The outside temperature sensor is defective. Check the connecting lead. |
| 1065 B | The pressure sensor is either defective or not connected. First, check the pressure sensor connection. If it needs replacing, contact a qualified heating engineer. |
| 1068 W | The outside temperature sensor is defective. Check the connecting lead. |
| 1073 W | Short circuit of the flow temperature sensor. Consider replacing the temperature sensor. |
| 1074 W | No signal from the flow temperature sensor detected or temperature sensor could need replacing. |
| 1075 W | The temperature sensor has a short circuit at the heating block |
| 1076 W | The temperature sensor gives no signal at the heating block is detected |
| 2920 V | Error with the flame monitoring |
| 2924 V | The modulating gas valve gives no feedback. The gas valve relay is defective. Press the reset button, then apply burner start. If the fault reoccurs, the gas valve may need replacements. |
| 2925 V | The feedback from the modulating gas valve is too low. |
| 2927 B | Flame failed during burner operation. Contact a qualified heating engineer. |
| 2946 V | Incorrect code plug detected. It may need replacing. |
| 2948,2959 B | No flame signal. The burner should turn on automatically after cleaning. Also, check the carbon dioxide setting. |
| 2963 B | The signal from the central heat flow and heat exchanger temperature sensor is outside the permissible range. Therefore, ensure the connecting leads are correctly connected. |
| 2964 B | The flow rate is too low in the heat exchanger. Contact a heating engineer. |
| 2965 B | The flow temperature is too high. Contact a heating engineer. |
| 2966 B | Flow temperature rise in heat exchanger is too rapid. Contact a heating engineer. |
| 2967 B | Central heat flow or temperature sensor differential is too great. Contact a heating engineer. |
| 2970 B | The pressure drop in the boiler system is too rapid. Repressurise the boiler. |
| 2971 B | System pressure is too low. The system needs venting or water topping to the desired pressure. |
Greenstar Ri boiler error codes.
| Fault Code | Possible cause/ How to fix it |
| No light | There is no power at the control board. |
| Light on | Appliance on but not operating during demand |
| Slow flash (mostly off flashes on) | Ignition lockout. |
| Slow flash (mostly on flashes off) | Flue overheats or heat exchanger overheat. |
| Fast flash | Volatile lockout sensor fan or code plug. |
| Two pulses | Check service mode switch is in minimum position. |
| Five pulses | Check service mode switch is in max position. |
Is my Worcester Bosch boiler faulty?
The Worcester boiler models made within the last decade usually display errors on code control panels when they detect an internal issue. As such, any errors within the boiler are likely to be displayed. However, it is convenient to regularly check your boiler for signs of faults to counter the problem way before the damage happens.
And as always, don’t attempt to fix the boiler if you do not understand an error. Instead, contact a qualified heating engineer who will safely and effectively repair your boiler or advice you accordingly.