2023 Worcester Bosch Boiler Error & Fault Codes
The Worcester Bosch Error Codes are an indicator for identifying the fault within your boiler and what needs to be done for fixing it. When you hear a beeping noise from your Worcester Bosch boiler and you see these error codes on your display; this is a clear indication that something is wrong with your boiler and you need to call a Worcester Bosch engineer immediately.
Error codes on your boiler can be a little bit daunting to diagnose and fix. There are a number of codes and many different error conditions that can arise, which means you could end up chasing your tail for a while. A code is triggered when there is some kind of fault inside the Worcester Bosch or something has gone wrong with the boiler, such as: illumination of the pilot light, water temperature is too low or high, it won’t start etc.
Our fault code guide will show you what error codes to look out for when needing to call for help, so your problem with your Worcester Bosch boiler is fixed and restored as soon as possible.
CDI Classic Combi Error Codes
Ever had the problem that your CDI Classic combi boiler is showing what appears to be just random numbers on the display? Don't worry. This is nothing to worry about. Here's a list of the meaning of each error code and whether it's serious or not, so you can make a decision about what action you need to take.
| Fault Code | Possible Cause |
|---|---|
| A1 | Water is leaking or the pump needs replacing or freeing due to the pump running dry. |
| A7 | The hot water negative thermistor coefficient (NTC) sensor is defective – the hot water sensor or connecting leads need checking. |
| A8 | Break communication to FX sensor controls electrical connections need checking. |
| B1 | Code plug not detected . |
| C6 | Fan speed too low – the fan lead and connector need checking and may need replacing. |
| E2 | Central heating (CH) water flow negative thermistor coefficient (NTC) sensor defective check CH flow NTC sensor and connection leads. |
| E9 | Safety temperature limiter in central heating (CH) flow has tripped the system pressure or safety temperature limiter needs checking. |
| EA | Flame not detected due to a gas issue – the gas supply, power supply or igniter, electrode and lead need checking – contact a Gas Safe installer. |
| F0 | Internal error – electrical connector contacts or programmer interface module – check ignition leads are not loose. |
| F7 | Flame detected even though the appliance is switched off – check the electrode assembly is dry and the pcb and flue are clear. |
| FA | Flame detected after gas shut off – the gas valve needs checking – hire a Gas Safe installer. |
| FD | Reset button pressed by mistake – press reset button again. |
CDI Compact Error Codes
Worn or broken components, problems with burners and pressure issues can each lead to problems with your Compact boiler. To get a list of error codes followed by a detailed description of what is wrong with your boiler, read below.
This table holds the most common boiler error codes from Worcester Bosch's CDI Compact. The model number of the boiler should be present on some form of user guide or service manual.
| Fault Code | Possible Cause |
|---|---|
| T1 | Ignition test – checking the igniter spark |
| T2 | Fan test – checking the basic fan |
| T3 | Pump test – checking 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 – problem with code plug |
| B7 257 | Internal error – possible control board problem |
| C6 215 | Fan problem – fan running too fast |
| C7 214 | Fan problem – fan not running |
| D1 240 | Return sensor error – sensor may be wet or damaged |
| E2 222 | Flow sensor short circuit error |
| E5 218 | Flow temperature too high |
| E9 219 | Safety sensor fault – temperature too high, sensor short circuit or open circuit |
| EA 227 | No flame detected or flame signal loss during operation |
| F0 237 | Internal error |
| F7 228 | Flame error – false flame or flame detected before burner started |
| FA 306 | False flame fault – flame detected after burner stop |
| FD 231 | Mains power fault – electrical power interruption |
| FA 364 | Gas valve EV2 leak test failed – gas valve leak |
| FB 365 | Gas valve EV1 leak test failed |
| A1 281 | Pump stuck or running with air in the system |
| C1 264 | Airflow stopped during operation |
| C4 273 | Airflow present during last 24 hour |
| D1 240 | Return sensor short circuit |
| D4 271 | Temperature difference between flow and safety sensor exceeds limit |
| E9 224 | Max thermostat activated – flue gas thermostat overheat |
| EA 227 | No ionisation detected after ignition |
| EF 349 | Central heating boil detected – boiler operating at minimum burner load with temperature difference greater than 18°C between Flow & Return. |
| NO CODE 212 | Safety or flow temperature rising too fast |
CDI Highflow Combi Error Codes
CDI Highflow Combi boilers are very common and loved by many. Unfortunately, they have a tendency to develop issues which in some cases can be complex. This is due to how technical they are.
There are a lot of different error codes which can pop up on your screen, so here's a list of the main error codes you may encounter along with what each means.
| Fault Code | Possible Cause |
|---|---|
| A1 | Pump dry run detection or pump is running in air the system pressure needs checking |
| A5 | Tank negative thermistor coefficient (NTC) defect |
| A7 | Domestic hot water (DHW) negative thermistor coefficient (NTC) defect |
| A8 | Energy Management System (EMS) communication error |
| B1 | Code plug not detected |
| B2 | Data error |
| B3 | Data error |
| B4 | Data error |
| B5 | Data error |
| 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 not detected |
| E2 | Primary negative thermistor coefficient (NTC) defect |
| E9 | Safety temperature limiter in central heating (CH) flow stat tripped |
| F0 | Internal error |
| F1 | ROM fault |
| F7 | Flame detected after appliance has been shut off |
| FA | Flame detected after gas shut off |
| FD | Reset button pressed – try pressing the reset button again |
CDI Classic Regular Error Codes
The Worcester Bosch CDI Classic Regular error codes are a list of errors that are displayed when the boiler has an issue within the control unit. It is designed to allow an engineer or service engineer to be able to diagnose the issue and ultimately fix it. This can range from issues such as flashing fault codes (a fault code that flashes on and off on the display screen), continuous fault codes (a fault code that stays on the screen).
The Worcester Bosch CDI Classic range has come a long way since the original design. The most common error is the classic “E” light on your display. That means something is wrong with your burner management system, so let’s take a look at all of the Worcester Bosch CDI Classic Regular boiler error codes and what they mean.
| Fault Code | Possible Cause |
|---|---|
| B1 | Code plug not detected |
| C6 | Fan speed too low |
| E2 | Central heating (CH) flow negative thermistor coefficient (NTC) sensor defective |
| E9 | Safety temperature limiter in central heating (CH) flow has tripped |
| EA | Flame not detected |
| F0 | Internal error |
| F7 | Flame detected even though appliance switched off |
| FA | Flame detected after gas shut off |
| FD | Reset button pressed by mistake |
GB162 Error Codes
Worcester Boiler GB162 error codes can be a real nightmare. Not only do you have to find out the error code you can’t just expect it to be the same every time. There are so many variables and combinations of factors, not to mention the fact that there could well be multiple problems. Having a list of Worcester Bosch error codes handy will make it easy for you to troubleshoot your system and find out exactly what the problem is.
Being able to identify what Worcester Bosch boiler error codes mean is essential if you are having problems. This guide lists all of the GB162 fault codes that you might find.
| Fault Code | Possible Cause |
|---|---|
| 208 | The boiler is in chimney sweep mode |
| 200 | The boiler is in heating mode |
| 201 | The boiler is in domestic hot water (DHW) mode |
| 202 | The boiler is waiting – there was a heat demand from the on off or modulating control |
| 203 | The boiler is on standby |
| 204 | The boiler is waiting – the actual temperature is higher than the calculated or selected boiler temperature |
| 212 | The temperature recorded by the flow temperature sensor or the safety sensor is rising too quickly |
| 226 | Diagnosis tool was connected and is now locked out |
| 260 | The flow temperature sensor is not detecting a rise in temperature following a burner start |
| 265 | The boiler is waiting in response to a heat demand – the boiler regularly switches to partial load |
| 268 | Component test phase |
| 270 | The boiler is modulating upwards |
| 283 | The boiler is preparing for a burner start – the fan and pump are activated |
| 284 | The gas valve is switched |
| 305 | The boiler is waiting for domestic hot water (DHW) operation to end |
| 235 | The KIM (boiler identification module) is too new for the burner control unit |
| 360 | The KIM that has been fitted is not compatible with the burner control unit |
| 9A 361 | The burner control unit that has been fitted is not compatible with the KIM (boiler identification module) |
| 9U 233 | The burner control unit or KIM (boiler identification module) is faulty |
| A3 317 | Short circuit in the flue gas temperature sensor contacts |
| B7 257 | The burner control unit or the KIM (boiler identification module) is faulty |
| C1 264 | No control signal or power supply to the fan during operation |
| C4 273 | The boiler was switched off for a maximum of 2 minutes because it had been operating continuously for more than 24 hours |
| C6 215 | The fan speed is too high |
| C6 216 | The fan speed is too low |
| C7 214 | The fan does not run during the start phase |
| C7 217 | The fan speed is irregular when starting up |
| CE 207 | Water pressure is too low |
| CE 266 | Pump test failed |
| D1 240 | The contacts of the boiler return temperature sensor have been short circuited |
| D1 241 | The contacts of the boiler return temperature sensor have been interrupted |
| D3 232 | The external switching contact has opened |
| D4 213 | The actual temperature recorded by the flow temperature sensor or return temperature sensor is rising too quickly |
| D4 271 | Actual temperature differential between flow and safety temperature sensor is too high |
| D4 286 | The boiler return temperature sensor has detected a return temperature higher than 105°c |
| E2 222 | Short circuit in the flow temperature sensor contacts |
| E2 223 | The flow temperature sensor contacts have been interrupted |
| E5 218 | The temperature captured by the flow temperature sensor exceeded 105°c |
| E9 210 | The temperature measured by the flue gas sensor is too high and is open |
| E9 219 | The safety temperature sensor has captured a temperature in excess of 105°C |
| E9 220 | The contacts for the safety temperature sensor have shorted or the safety temperature sensor has detected a temperature higher than 130°c |
| E9 224 | The contacts of the safety temperature sensor have been interrupted |
| E9 276 | The temperature flow sensor has measured a temperature in excess of 95°c |
| E9 277 | The safety temperature sensor has measured temperature in excess of 95°c |
| E9 285 | The boiler return temperature sensor has measured a temperature higher than 95°c |
| E9 318 | The flue gas temperature sensor contacts have been interrupted |
| EA 227 | An insufficient ionisation current was measured following ignition of the burner |
| EA 229 | The ionisation current detected by the system during the burning phase was insufficient |
| EA 234 | The contacts of the gas valve have been interrupted |
| EA 261 | The burner control unit is faulty |
| EA 269 | The ignition device has been activated for too long |
| F0 238 | The burner control unit KIM (boiler identification module) is faulty |
| F0 239 | The burner control unit KIM (boiler identification module) has an error. Cabling might have poor contact breaks and pinching or the plug and wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 240 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 241 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 242 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 243 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 244 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 245 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 246 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 247 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 248 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 249 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 250 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 251 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 252 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 253 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 255 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 259 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 263 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 267 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 272 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
| F0 278 | The sensor test has failed – cabling and plug sensors need checking |
| F0 279 | The burner control unit, or KIM, is faulty – control unit may need replacing |
| F0 280 | The burner control unit is faulty |
| F0 287 | The burner control unit, or KIM, has an error |
| F0 290 | The burner control unit, or KIM, is faulty |
| F7 228 | An ionisation current was measured before the burner started |
| F7 328 | A brief power failure has occurred |
| FA 306 | An ionisation current was measured after the burner went out |
| FD 231 | The mains voltage was interrupted during an interlocking fault |
| EC 256 | The burner control unit has an error |
| EH 258 | The burner control unit is faulty – check the plug and wiring of the burner control unit. |
| H07 | The current water pressure is too low, limiting the performance in heat mode as well as domestic hot water (DHW) mode |
| HrE | The boiler keeps resetting |
| rE | The boiler resets |
Greenstar 25/30Si Combi Error Codes
The greenstar 25/30Si combi boiler is a popular choice of boiler for many home owners. The comile is an update to the Greenstar 25 and offers much more flexibility when it comes to selecting a programmer that is compatible with your needs. I feel this new model is a huge success as it has offered so many happy homeowners the chance to get economical and efficient heating solutions for their homes.
Greenstar 25/30Si Combi boilers use a series of error codes to tell you when something is wrong with your boiler. Error codes can be frustrating as they make it difficult to identify the problem clearly so this table will help you understand what each error code means.
| Fault Code | Possible Cause |
|---|---|
| T1 | Ignition test – checking the igniter spark |
| T2 | Fan test – checking the basic fan |
| T3 | Pump test – checking 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 – problem with code plug |
| B7 257 | Internal error – possible control board problem |
| C6 215 | Fan problem – fan running too fast |
| C7 214 | Fan problem – fan not running |
| D1 240 | Return sensor error – sensor may be wet or damaged |
| E2 222 | Flow sensor short circuit error |
| E5 218 | Flow temperature too high |
| E9 219 | Safety sensor fault – temperature too high, sensor short circuit or open circuit |
| EA 227 | No flame detected or flame signal loss during operation |
| F0 237 | Internal error |
| F7 228 | Flame error – false flame or flame detected before burner started |
| FA 306 | False flame fault – flame detected after burner stop |
| FD 231 | Mains power fault – electrical power interruption |
| FA 364 | Gas valve EV2 leak test failed – gas valve leak |
| FB 365 | Gas valve EV1 leak test failed |
| A1 281 | Pump stuck or running with air in the system |
| C1 264 | Airflow stopped during operation |
| C4 273 | Airflow present during last 24 hour |
| D1 240 | Return sensor short circuit |
| D4 271 | Temperature difference between flow and safety sensor exceeds limit |
| E9 224 | Max thermostat activated – flue gas thermostat overheat |
| EA 227 | No ionisation detected after ignition |
| EF 349 | Central heating boil detected – boiler operating at minimum burner load with temperature difference greater than 18°C between Flow & Return. |
| NO CODE 212 | Safety or flow temperature rising too fast |
Greenstar 27/20 System Error Codes
The Worcester Bosch Greenstar 27/20 system has a large number of error codes you could get. Some are more serious than others, however some can be easily rectified with some research and understanding.
These error codes indicate a fault and will display on the unit’s digital screen. You can refer to the table in this article to find an error code and its meaning. It’s important to know what error code your Greenstar 27/20 System is displaying, so you can remedy the problem. Please note there are a few instances when no code displays on the Greenstar system; these particular instances result from a problem with the control box, wiring, or both.
| Fault Code | Possible Cause |
|---|---|
| T1 | Ignition test – checking the igniter spark |
| T2 | Fan test – checking the basic fan |
| T3 | Pump test – checking 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 – problem with code plug |
| B7 257 | Internal error – possible control board problem |
| C6 215 | Fan problem – fan running too fast |
| C7 214 | Fan problem – fan not running |
| D1 240 | Return sensor error – sensor may be wet or damaged |
| E2 222 | Flow sensor short circuit error |
| E5 218 | Flow temperature too high |
| E9 219 | Safety sensor fault – temperature too high, sensor short circuit or open circuit |
| EA 227 | No flame detected or flame signal loss during operation |
| F0 237 | Internal error |
| F7 228 | Flame error – false flame or flame detected before burner started |
| FA 306 | False flame fault – flame detected after burner stop |
| FD 231 | Mains power fault – electrical power interruption |
| FA 364 | Gas valve EV2 leak test failed – gas valve leak |
| FB 365 | Gas valve EV1 leak test failed |
| A1 281 | Pump stuck or running with air in the system |
| C1 264 | Airflow stopped during operation |
| C4 273 | Airflow present during last 24 hour |
| D1 240 | Return sensor short circuit |
| D4 271 | Temperature difference between flow and safety sensor exceeds limit |
| E9 224 | Max thermostat activated – flue gas thermostat overheat |
| EA 227 | No ionisation detected after ignition |
| EF 349 | Central heating boil detected – boiler operating at minimum burner load with temperature difference greater than 18°C between Flow & Return. |
| NO CODE 212 | Safety or flow temperature rising too fast |
Greenstar I System Error Codes
All Greenstar I System boilers have a set of error codes built into the system. This list of boiler error codes will help you diagnose any faults that have been encountered on your system. Understanding what has caused the error code means you can attempt to manually reset your boiler, which may clear the issue up. If not, you'll need to call out a registered installer for assistance.
| Fault Code | Possible Cause |
|---|---|
| 226 | Service tool has been connected in the blocking error history menu |
| FD 231 | The power has been interrupted during a lockout |
| C7 214 | Fan does not run during the start up phase – fan harness connector needs checking |
| C6 215 | Fan speed too high – check the fan harness and connector |
| C7 216 | Fan speed too low – check the fan harness and connector |
| C7 217 | Fan has stopped during appliance operation |
| C1 264 | Fan stopped during operation |
| C4 273 | Continuous fan operation for the last 24 hours – appliance temporarily blocked |
| E2 222 | Flow temperature sensor shorted |
| E2 233 | Flow temperature sensor disconnected |
| E9 276 | Primary flow temperature exceeded 95°c |
| E2 350 | Flow temperature sensor shorted |
| E2 351 | Flow temperature sensor disconnected |
| FA 306 | Ionisation detected after the gas valve closed |
| EA 227 | No ionisation detected after ignition |
| F7 228 | Isioniation current detected before burner start |
| EA 229 | Loss of ionisation signal during operation |
| EA 261 | Heat control module (HCM) potentially defective – reset the appliance |
| 9U 233 | Control box or heat control module (HCM) is defective or loose, the HCM needs to be checked |
| C4 237 | Control box or heat control module (HCM) is defective |
| F0 238 | Gas valve or control box error – gas valve coils need checking |
| F0 239 | Control box or the heat control module (HCM) is defective – the control box connections need checking |
| F0 242 | Control box or the heat control module (HCM) is defective – the HCM and control box connections need to be checked |
| B7 257 | Control box or the heat control module HCM) is defective- the HCM and control box connections need to be checked |
| F0 258 | Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked |
| EH 258 | Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked |
| F1 259 | Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked |
| F0 262 | Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked |
| F1 263 | Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked |
| F0 272 | Control box or the heat control module (HCM) is defective – control box and connections need checking or HCM might not be inserted properly and need replacing |
| F0 280 | Control box or the heat control module (HCM) is defective – control box and connections need checking or HCM might not be inserted properly and need replacing |
| F0 290 | Control box is defective – HCM needs checking as it might not be inserted properly or need replacing |
| 328 | Internal error with the mains voltage – frequency may be inconsistent |
| 235 | Incompatible heat control module (HCM) software versions – control box needs latest software |
| 356 | Low mains voltage – the voltage may be interrupted or inconsistent and needs checking |
| 360 | Heat control module (HCM) invalid – the inserted HCM does not correspond with the control box |
| A8 362 | Low mains voltage – the voltage may be interrupted, inconsistent or heat control module (HCM) invalid |
| CC 800 | Outdoor sensor defect available when accessory outdoor 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 |
Greenstar 8000 Error Codes
Many Greenstar 8000 error codes are generated by faults with sensors or equipment. These include but are not limited to flame failure, pump failure, and obstruction in the flow passages. This guide will help you identify common error codes associated with boiler’s operation that may occur when operating Worcester Bosch Greenstar 8000 boilers.
There are two main boilers in this range, the Greenstar 8000 and Greenstar 8000 eco models. These two models are slightly different, but more or less the same in terms of error codes.
| Fault Code | Possible Cause |
|---|---|
| 200 O | Boiler in heating mode |
| 201 O | Boiler in hot water mode |
| 202 O | Boiler in anti-cycle mode |
| 203 0 | Boiler in standby – no heat energy demand |
| 204 O | Current primary water temperature higher than set value |
| 208 0 | Chimney sweep demand |
| 224 V | Safety temperature limiter has tripped – top-up water until the reset pressure is reached |
| 227 V | No flame signal after ignition burner control unit could need replacing |
| 228 V | Flame signal without flame present – air/gas ratio control valve may need replacing as might the ionisation cable |
| 305 0 | Boiler in hot water anti-cycle mode |
| 306 V | Flame signal after closing the fuel supply – the air/gas ratio control valve might need replacing |
| 360 V | Incompatible code plug – check if a correct code plug is installed and exchange or reconnect code plug |
| 815 W/B | Low loss header temperature sensor faulty – check the sensor port or check the differential sensor for incorrect installation position or breakage |
| 1010 O | No BUS communication cable, EMS-Bus isn’t connected or damaged – connect the cable for the EMS-Bus or replace the damaged cable exchange fuse |
| 1017 W | Water pressure too low – the water needs topping up and the vent system or pressure sensor may need replacing |
| 1021 B | Hot water temperature sensor is defective – the plug to the hot water temperature sensor may not be connected |
| 1022 B | Hot water storage temperature sensor is defective – connect the plug to the hot water temperature sensor correctly, mount the hot water temperature sensor correctly or replace the hot water temperature sensor |
| 1037 W | Outside temperature sensor is defective – check the connecting lead |
| 1065 B | Pressure sensor defective or not connected – check pressure sensor connection as it may need replacing |
| 1068 W | Outside temperature sensor defective – check the connecting lead |
| 1073 W | Short circuit of the flow temperature sensor – the temperature sensor may need replacing |
| 1074 W | No signal from the flow temperature sensor available – connect the plug to the flow temperature sensor correctly or temperature sensor could need replacing |
| 1075 W | Short circuit of the temperature sensor at the heating block – temperature sensor may need replacing |
| 1076 W | No signal from the temperature sensor at the heating block available – replace the temperature sensor, the connecting lead or the control unit |
| 2920 V | Error with the flame monitoring |
| 2924 V | No feedback from the modulating gas valve. The gas valve relay is defective – press the reset button and apply burner start, wait to see if fault reoccurs, if it does the gas valve needs replacing |
| 2925 V | Feedback from the modulating gas valve is too low |
| 2927 B | Flame failed during burner operation. Open the main shut off valve, shut down the appliance and check gas line, replace the ionisation electrode, set burner correctly and minimum rated load, check the integrity flue system and if the interconnected room air supply is too small, or the size of the ventilation opening is too small, clean the heating block on the flue gas side or replace the control unit/burner control unit |
| 2946 V | Incorrect code plug detected – the code plug needs replacing |
| 2948 B | No flame signal. With low output the burner starts automatically after cleaning. If the fault occurs repeatedly, the setting of the CO2 valves need checking |
| 2950 B | No flame signal. Following starting procedure the burner starts automatically. After cleaning set the correct gas / air ratio correctly |
| 2963 B | Signal from flow and heat exchanger temperature sensor outside the permissible range – the connecting lead needs connecting correctly |
| 2964 B | Flow rate in heat exchanger is too low |
| 2965 B | Flow temperature too high |
| 2966 B | Flow temperature rise in heat exchanger too rapid |
| 2967 B | Flow / heat exchanger temperature sensor differential too great |
| 2970 B | Pressure drop in heating system too rapid |
| 2971 B | System pressure too low – the heating system needs venting or water needs topping up until the preset pressure is reached. Replace the cable to the pressure sensor replace the pressure sensor |
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