Product error-code directory

Boilers and HVAC error codes

Search fault, warning and status codes for boilers, air conditioners, heat pumps, thermostats and ventilation equipment. Find quick meanings, model context, safe checks and available source guidance.

2,693documented codes
32manufacturers
30product groups

About Boilers and HVAC error codes

Error codes are diagnostic indicators generated when a product detects an operating condition outside its expected range. They help narrow the search, but they do not automatically prove that a named component has failed. The same code can have different meanings across manufacturers, products, model generations and regions.

This category directory covers boilers, air conditioners, heat pumps, thermostats and ventilation equipment. Start with the exact characters shown on the display, then confirm the manufacturer, product type and full model number. Every indexed result links to a dedicated page containing a quick answer, likely symptoms and causes, safe troubleshooting boundaries, reset guidance, applicable products and source information.

Do not repeatedly reset a returning fault or use instructions written for a different model. Isolate electrical products before accessible checks and stop where gas, refrigerant, high voltage, stored energy, hot components or moving machinery may be involved. Use an authorised technician whenever diagnosis requires covers to be removed or safety-critical systems to be tested.

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E12Baxi · Baxi legacy combi and system boilers · United KingdomDifferential water flow switch fault (still open).Baxi documents E12 for the Baxi legacy combi and system boilers as “Differential water flow switch fault (still…E125Baxi · Baxi legacy combi and system boilers · United KingdomWater circulation fault.Baxi documents E125 for the Baxi legacy combi and system boilers as “Water circulation fault.”. This is the…E128Baxi · Baxi legacy combi and system boilers · United KingdomSafety error for frequent loss of flame.Baxi documents E128 for the Baxi legacy combi and system boilers as “Safety error for frequent loss of…E129Baxi · Baxi legacy combi and system boilers · United KingdomSafety error for frequent loss of flame with max correction during ignition during Calibration Function.Baxi documents E129 for the Baxi legacy combi and system boilers as “Safety error for frequent loss of…E13Baxi · Baxi legacy combi and system boilers · United KingdomDifferential water flow switch fault (still closed).Baxi documents E13 for the Baxi legacy combi and system boilers as “Differential water flow switch fault (still…E130Baxi · Baxi legacy combi and system boilers · United KingdomFlue thermostat sensor tripped (lockout).Baxi documents E130 for the Baxi legacy combi and system boilers as “Flue thermostat sensor tripped (lockout).”. This…E133Baxi · Baxi legacy combi and system boilers · United KingdomGas supply fault. Check the power supply, sensing electrode, spark electrode and cable.Baxi documents E133 for the Baxi legacy combi and system boilers as “Gas supply fault. Check the power…E134Baxi · Baxi legacy combi and system boilers · United KingdomElapsed time gas valve open without gas (short request in a short period).Baxi documents E134 for the Baxi legacy combi and system boilers as “Elapsed time gas valve open without…E135Baxi · Baxi legacy combi and system boilers · United KingdomInternal error.Baxi documents E135 for the Baxi legacy combi and system boilers as “Internal error.”. This is the quick…E15Baxi · Baxi legacy combi and system boilers · United KingdomGas valve command fault.Baxi documents E15 for the Baxi legacy combi and system boilers as “Gas valve command fault.”. This is…E154Baxi · Baxi legacy combi and system boilers · United KingdomPlausibility test (flow/return).Baxi documents E154 for the Baxi legacy combi and system boilers as “Plausibility test (flow/return).”. This is the…E160Baxi · Baxi legacy combi and system boilers · United KingdomFan fault.Baxi documents E160 for the Baxi legacy combi and system boilers as “Fan fault.”. This is the quick…E20Baxi · Baxi legacy combi and system boilers · United KingdomCentral heating NTC sensor fault - short circuit/open circuit.Baxi documents E20 for the Baxi legacy combi and system boilers as “Central heating NTC sensor fault -…E270Baxi · Baxi legacy combi and system boilers · United KingdomDry fire.Baxi documents E270 for the Baxi legacy combi and system boilers as “Dry fire.”. This is the quick…E28Baxi · Baxi legacy combi and system boilers · United KingdomFlue NTC sensor fault- short circuit/open circuit.Baxi documents E28 for the Baxi legacy combi and system boilers as “Flue NTC sensor fault- short circuit/open…E317Baxi · Baxi legacy combi and system boilers · United KingdomWrong power supply electrical frequency (Hz).Baxi documents E317 for the Baxi legacy combi and system boilers as “Wrong power supply electrical frequency (Hz).”.…E321Baxi · Baxi legacy combi and system boilers · United KingdomDomestic Hot Water NTC sensor fault (s.c.).Baxi documents E321 for the Baxi legacy combi and system boilers as “Domestic Hot Water NTC sensor fault…E384Baxi · Baxi legacy combi and system boilers · United KingdomFalse flame (parasitic flame).Baxi documents E384 for the Baxi legacy combi and system boilers as “False flame (parasitic flame).”. This is…E385Baxi · Baxi legacy combi and system boilers · United KingdomUnder voltage.Baxi documents E385 for the Baxi legacy combi and system boilers as “Under voltage.”. This is the quick…E40Baxi · Baxi legacy combi and system boilers · United KingdomReturn central heating NTC sensor fault- short circuit/open circuit.Baxi documents E40 for the Baxi legacy combi and system boilers as “Return central heating NTC sensor fault-…E430Baxi · Baxi legacy combi and system boilers · United KingdomWater pressure temporary fault.Baxi documents E430 for the Baxi legacy combi and system boilers as “Water pressure temporary fault.”. This is…E50Baxi · Baxi legacy combi and system boilers · United KingdomDHW NTC sensor fault (tank boiler) - short circuit/open circuit.Baxi documents E50 for the Baxi legacy combi and system boilers as “DHW NTC sensor fault (tank boiler)…E83Baxi · Baxi legacy combi and system boilers · United KingdomNo communication.Baxi documents E83 for the Baxi legacy combi and system boilers as “No communication.”. This is the quick…AN 11Biasi · Activ A condensing boiler · United KingdomAN 11 — Parasitic flame detectedBiasi Activ A documentation identifies AN 11 as “Parasitic flame detected”. Confirm the exact model because similarly numbered…ER 01Biasi · Activ A condensing boiler · United KingdomER 01 — Burner ignition failureBiasi Activ A documentation identifies ER 01 as “Burner ignition failure”. Confirm the exact model because similarly numbered…ER 02Biasi · Activ A condensing boiler · United KingdomER 02 — Safety thermostat lockoutBiasi Activ A documentation identifies ER 02 as “Safety thermostat lockout”. Confirm the exact model because similarly numbered…ER 03Biasi · Activ A condensing boiler · United KingdomER 03 — General lockoutBiasi Activ A documentation identifies ER 03 as “General lockout”. Confirm the exact model because similarly numbered codes…ER 04Biasi · Activ A condensing boiler · United KingdomER 04 — Primary circuit has insufficient water or flowBiasi Activ A documentation identifies ER 04 as “Primary circuit has insufficient water or flow”. Confirm the exact…ER 05Biasi · Activ A condensing boiler · United KingdomER 05 — Fan-control system faultBiasi Activ A documentation identifies ER 05 as “Fan-control system fault”. Confirm the exact model because similarly numbered…ER 06Biasi · Activ A condensing boiler · United KingdomER 06 — Central-heating temperature probe faultBiasi Activ A documentation identifies ER 06 as “Central-heating temperature probe fault”. Confirm the exact model because similarly…ER 08Biasi · Activ A condensing boiler · United KingdomER 08 — External temperature probe faultBiasi Activ A documentation identifies ER 08 as “External temperature probe fault”. Confirm the exact model because similarly…ER 09Biasi · Activ A condensing boiler · United KingdomER 09 — Flue temperature probe faultBiasi Activ A documentation identifies ER 09 as “Flue temperature probe fault”. Confirm the exact model because similarly…ER 10Biasi · Activ A condensing boiler · United KingdomER 10 — Flue-temperature safety interventionBiasi Activ A documentation identifies ER 10 as “Flue-temperature safety intervention”. Confirm the exact model because similarly numbered…ER 14Biasi · Activ A condensing boiler · United KingdomER 14 — Pump fault, no circulation or primary overtemperatureBiasi Activ A documentation identifies ER 14 as “Pump fault, no circulation or primary overtemperature”. Confirm the exact…ER 15Biasi · Activ A condensing boiler · United KingdomER 15 — Insufficient water flow or excessive sensor differenceBiasi Activ A documentation identifies ER 15 as “Insufficient water flow or excessive sensor difference”. Confirm the exact…ER 16Biasi · Activ A condensing boiler · United KingdomER 16 — Flow and return probes exchanged or pump incorrectly installedBiasi Activ A documentation identifies ER 16 as “Flow and return probes exchanged or pump incorrectly installed”. Confirm…ER 17Biasi · Activ A condensing boiler · United KingdomER 17 — Flow or return central-heating probe faultBiasi Activ A documentation identifies ER 17 as “Flow or return central-heating probe fault”. Confirm the exact model…ER 18Biasi · Activ A condensing boiler · United KingdomER 18 — Primary circuit has insufficient water or improper flowBiasi Activ A documentation identifies ER 18 as “Primary circuit has insufficient water or improper flow”. Confirm the…L3Biasi · Activ A condensing boiler · United KingdomL3 — Output limited by excessive temperature differenceBiasi Activ A documentation identifies L3 as “Output limited by excessive temperature difference”. Confirm the exact model because…101Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 101 error code – Primary circuit overheatingChaffoteaux documents 101 for the INOA NOx wall-hung gas boiler as: Primary circuit overheating.103Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 103 error code – Heating circulation anomalyChaffoteaux documents 103 for the INOA NOx wall-hung gas boiler as: Heating circulation anomaly.104Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 104 error code – Heating circulation anomalyChaffoteaux documents 104 for the INOA NOx wall-hung gas boiler as: Heating circulation anomaly.105Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 105 error code – Heating circulation anomalyChaffoteaux documents 105 for the INOA NOx wall-hung gas boiler as: Heating circulation anomaly.106Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 106 error code – Heating circulation anomalyChaffoteaux documents 106 for the INOA NOx wall-hung gas boiler as: Heating circulation anomaly.107Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 107 error code – Heating circulation anomalyChaffoteaux documents 107 for the INOA NOx wall-hung gas boiler as: Heating circulation anomaly.110Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 110 error code – Main heat-exchanger outlet sensor faultChaffoteaux documents 110 for the INOA NOx wall-hung gas boiler as: Main heat-exchanger outlet sensor fault.112Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 112 error code – Main heat-exchanger inlet sensor faultChaffoteaux documents 112 for the INOA NOx wall-hung gas boiler as: Main heat-exchanger inlet sensor fault.114Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 114 error code – Outdoor sensor faultChaffoteaux documents 114 for the INOA NOx wall-hung gas boiler as: Outdoor sensor fault.116Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 116 error code – Underfloor-heating thermostat openChaffoteaux documents 116 for the INOA NOx wall-hung gas boiler as: Underfloor-heating thermostat open.118Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 118 error code – Primary circuit sensor faultChaffoteaux documents 118 for the INOA NOx wall-hung gas boiler as: Primary circuit sensor fault.1P1Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 1P1 error code – Heating circulation pre-warningChaffoteaux documents 1P1 for the INOA NOx wall-hung gas boiler as: Heating circulation pre-warning.1P2Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 1P2 error code – Heating circulation pre-warningChaffoteaux documents 1P2 for the INOA NOx wall-hung gas boiler as: Heating circulation pre-warning.1P3Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 1P3 error code – Heating circulation pre-warningChaffoteaux documents 1P3 for the INOA NOx wall-hung gas boiler as: Heating circulation pre-warning.205Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 205 error code – Solar domestic-hot-water inlet sensor faultChaffoteaux documents 205 for the INOA NOx wall-hung gas boiler as: Solar domestic-hot-water inlet sensor fault.301Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 301 error code – Display EEPROM faultChaffoteaux documents 301 for the INOA NOx wall-hung gas boiler as: Display EEPROM fault.302Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 302 error code – GP-GIU communication faultChaffoteaux documents 302 for the INOA NOx wall-hung gas boiler as: GP-GIU communication fault.303Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 303 error code – Main control board faultChaffoteaux documents 303 for the INOA NOx wall-hung gas boiler as: Main control board fault.304Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 304 error code – Too many reset attemptsChaffoteaux documents 304 for the INOA NOx wall-hung gas boiler as: Too many reset attempts.305Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 305 error code – Main control board faultChaffoteaux documents 305 for the INOA NOx wall-hung gas boiler as: Main control board fault.306Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 306 error code – Main control board faultChaffoteaux documents 306 for the INOA NOx wall-hung gas boiler as: Main control board fault.307Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 307 error code – Main control board faultChaffoteaux documents 307 for the INOA NOx wall-hung gas boiler as: Main control board fault.313Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 313 error code – Low supply voltageChaffoteaux documents 313 for the INOA NOx wall-hung gas boiler as: Low supply voltage.3P9Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 3P9 error code – Service requiredChaffoteaux documents 3P9 for the INOA NOx wall-hung gas boiler as: Service required.411Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 411 error code – Zone 1 room sensor unavailableChaffoteaux documents 411 for the INOA NOx wall-hung gas boiler as: Zone 1 room sensor unavailable.412Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 412 error code – Zone 2 room sensor unavailableChaffoteaux documents 412 for the INOA NOx wall-hung gas boiler as: Zone 2 room sensor unavailable.413Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 413 error code – Zone 3 room sensor unavailableChaffoteaux documents 413 for the INOA NOx wall-hung gas boiler as: Zone 3 room sensor unavailable.501Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 501 error code – No flame detectedChaffoteaux documents 501 for the INOA NOx wall-hung gas boiler as: No flame detected.502Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 502 error code – Flame detected with gas valve closedChaffoteaux documents 502 for the INOA NOx wall-hung gas boiler as: Flame detected with gas valve closed.503Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 503 error code – Persistent flame detected with gas valve closedChaffoteaux documents 503 for the INOA NOx wall-hung gas boiler as: Persistent flame detected with gas valve closed.504Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 504 error code – Burner ionisation fault during operationChaffoteaux documents 504 for the INOA NOx wall-hung gas boiler as: Burner ionisation fault during operation.5P3Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 5P3 error code – Flame lift detectedChaffoteaux documents 5P3 for the INOA NOx wall-hung gas boiler as: Flame lift detected.5P5Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 5P5 error code – Low gas pressureChaffoteaux documents 5P5 for the INOA NOx wall-hung gas boiler as: Low gas pressure.5P6Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 5P6 error code – Ignition attempt failedChaffoteaux documents 5P6 for the INOA NOx wall-hung gas boiler as: Ignition attempt failed.601Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 601 error code – Flue-safety sensor intervention on CF modelChaffoteaux documents 601 for the INOA NOx wall-hung gas boiler as: Flue-safety sensor intervention on CF model.602Chaffoteaux · INOA NOx wall-hung gas boiler · France and EuropeChaffoteaux INOA NOx wall-hung gas boiler 602 error code – VMC flue-safety sensor faultChaffoteaux documents 602 for the INOA NOx wall-hung gas boiler as: VMC flue-safety sensor fault.2De Dietrich · C 230 ECO floor-standing condensing boiler · Europe and North AmericaDe Dietrich C 230 ECO 2 error code – Heat-exchanger sensor short circuitThe heat-exchanger temperature sensor circuit is short-circuited.3De Dietrich · C 230 ECO floor-standing condensing boiler · Europe and North AmericaDe Dietrich C 230 ECO 3 error code – Heat-exchanger sensor disconnectedThe heat-exchanger temperature sensor is open-circuit or disconnected.32De Dietrich · C 230 ECO floor-standing condensing boiler · Europe and North AmericaDe Dietrich C 230 ECO 32 error code – Boiler sensor short circuitThe main boiler temperature sensor circuit is short-circuited.33De Dietrich · C 230 ECO floor-standing condensing boiler · Europe and North AmericaDe Dietrich C 230 ECO 33 error code – Boiler sensor disconnectedThe main boiler temperature sensor is open-circuit or disconnected.4De Dietrich · C 230 ECO floor-standing condensing boiler · Europe and North AmericaDe Dietrich C 230 ECO 4 error code – Heat-exchanger sensor reading below −10°CThe heat-exchanger sensor reports a temperature below −10°C.6De Dietrich · C 230 ECO floor-standing condensing boiler · Europe and North AmericaDe Dietrich C 230 ECO 6 error code – Return sensor short circuitThe boiler return-temperature sensor circuit is short-circuited.7De Dietrich · C 230 ECO floor-standing condensing boiler · Europe and North AmericaDe Dietrich C 230 ECO 7 error code – Return sensor disconnectedThe boiler return-temperature sensor is open-circuit or disconnected.8De Dietrich · C 230 ECO floor-standing condensing boiler · Europe and North AmericaDe Dietrich C 230 ECO 8 error code – Return sensor reading below −10°CThe return-temperature sensor reports a temperature below −10°C.101ELCO · TRIGON L PLUS commercial condensing boiler · United Kingdom and EuropeELCO TRIGON L PLUS commercial condensing boiler 101 error code – Engine overheatELCO identifies 101 for the TRIGON L PLUS commercial condensing boiler as: Engine overheat.104ELCO · TRIGON L PLUS commercial condensing boiler · United Kingdom and EuropeELCO TRIGON L PLUS commercial condensing boiler 104 error code – Flow Check 2ELCO identifies 104 for the TRIGON L PLUS commercial condensing boiler as: Flow Check 2.107ELCO · TRIGON L PLUS commercial condensing boiler · United Kingdom and EuropeELCO TRIGON L PLUS commercial condensing boiler 107 error code – Flow Check 5ELCO identifies 107 for the TRIGON L PLUS commercial condensing boiler as: Flow Check 5.110ELCO · TRIGON L PLUS commercial condensing boiler · United Kingdom and EuropeELCO TRIGON L PLUS commercial condensing boiler 110 error code – Flow or send probe damagedELCO identifies 110 for the TRIGON L PLUS commercial condensing boiler as: Flow or send probe damaged.1P1ELCO · TRIGON L PLUS commercial condensing boiler · United Kingdom and EuropeELCO TRIGON L PLUS commercial condensing boiler 1P1 error code – Flow Check 1ELCO identifies 1P1 for the TRIGON L PLUS commercial condensing boiler as: Flow Check 1.1P2ELCO · TRIGON L PLUS commercial condensing boiler · United Kingdom and EuropeELCO TRIGON L PLUS commercial condensing boiler 1P2 error code – Flow Check 3ELCO identifies 1P2 for the TRIGON L PLUS commercial condensing boiler as: Flow Check 3.1P3ELCO · TRIGON L PLUS commercial condensing boiler · United Kingdom and EuropeELCO TRIGON L PLUS commercial condensing boiler 1P3 error code – Flow Check 4ELCO identifies 1P3 for the TRIGON L PLUS commercial condensing boiler as: Flow Check 4.328ELCO · TRIGON XXL commercial condensing boiler · United Kingdom and EuropeELCO TRIGON XXL 328 error code – Mixing groups configured with the same functionELCO documents lockout code 328 for the TRIGON XXL as: Mixing groups configured with the same function.329ELCO · TRIGON XXL commercial condensing boiler · United Kingdom and EuropeELCO TRIGON XXL 329 error code – Extension module or mixing group configured with the same functionELCO documents lockout code 329 for the TRIGON XXL as: Extension module or mixing group configured with the…330ELCO · TRIGON XXL commercial condensing boiler · United Kingdom and EuropeELCO TRIGON XXL 330 error code – BX1 sensor has no functionELCO documents lockout code 330 for the TRIGON XXL as: BX1 sensor has no function.331ELCO · TRIGON XXL commercial condensing boiler · United Kingdom and EuropeELCO TRIGON XXL 331 error code – BX2 sensor has no functionELCO documents lockout code 331 for the TRIGON XXL as: BX2 sensor has no function.332ELCO · TRIGON XXL commercial condensing boiler · United Kingdom and EuropeELCO TRIGON XXL 332 error code – BX3 sensor has no functionELCO documents lockout code 332 for the TRIGON XXL as: BX3 sensor has no function.333ELCO · TRIGON XXL commercial condensing boiler · United Kingdom and EuropeELCO TRIGON XXL 333 error code – BX4 sensor has no functionELCO documents lockout code 333 for the TRIGON XXL as: BX4 sensor has no function.334ELCO · TRIGON XXL commercial condensing boiler · United Kingdom and EuropeELCO TRIGON XXL 334 error code – BX5 sensor has no functionELCO documents lockout code 334 for the TRIGON XXL as: BX5 sensor has no function.335ELCO · TRIGON XXL commercial condensing boiler · United Kingdom and EuropeELCO TRIGON XXL 335 error code – BX21 sensor has no function on extension moduleELCO documents lockout code 335 for the TRIGON XXL as: BX21 sensor has no function on extension module.336ELCO · TRIGON XXL commercial condensing boiler · United Kingdom and EuropeELCO TRIGON XXL 336 error code – BX22 sensor has no function on extension moduleELCO documents lockout code 336 for the TRIGON XXL as: BX22 sensor has no function on extension module.337ELCO · TRIGON XXL commercial condensing boiler · United Kingdom and EuropeELCO TRIGON XXL 337 error code – BX1 sensor has no functionELCO documents lockout code 337 for the TRIGON XXL as: BX1 sensor has no function.