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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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 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 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 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 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 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…ALL 99Sime · Brava Slim HE ErP condensing boiler · United Kingdom and EuropeALL 99 — General electronic-board errorSime documents ALL 99 for the Brava Slim HE ErP range as “General electronic-board error”. The alarm identifies…ALL 98Sime · Brava Slim HE ErP condensing boiler · United Kingdom and EuropeALL 98 — Electronic-board start-up errorSime documents ALL 98 for the Brava Slim HE ErP range as “Electronic-board start-up error”. The alarm identifies…
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E01ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E01 error code – Failed ignition after three attemptsACV documents E01 for the Compact Condens 170, 210, 250 and 300 as: Failed ignition after three attempts.E02ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E02 error code – False flame detected before ignitionACV documents E02 for the Compact Condens 170, 210, 250 and 300 as: False flame detected before ignition.E03ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E03 error code – Boiler temperature above 105°CACV documents E03 for the Compact Condens 170, 210, 250 and 300 as: Boiler temperature above 105°C.E04ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E04 error code – Air-pressure switch failed zero-position checkACV documents E04 for the Compact Condens 170, 210, 250 and 300 as: Air-pressure switch failed zero-position check.E05ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E05 error code – Blower speed incorrect or signal missingACV documents E05 for the Compact Condens 170, 210, 250 and 300 as: Blower speed incorrect or signal…E06ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E06 error code – Air-pressure switch opened repeatedly during operationACV documents E06 for the Compact Condens 170, 210, 250 and 300 as: Air-pressure switch opened repeatedly during…E07ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E07 error code – Flue temperature above limitACV documents E07 for the Compact Condens 170, 210, 250 and 300 as: Flue temperature above limit.E08ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E08 error code – Flame-circuit test failedACV documents E08 for the Compact Condens 170, 210, 250 and 300 as: Flame-circuit test failed.E09ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E09 error code – Gas-valve circuit test failedACV documents E09 for the Compact Condens 170, 210, 250 and 300 as: Gas-valve circuit test failed.E12ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E12 error code – EEPROM configuration faultACV documents E12 for the Compact Condens 170, 210, 250 and 300 as: EEPROM configuration fault.E13ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E13 error code – Reset limit reachedACV documents E13 for the Compact Condens 170, 210, 250 and 300 as: Reset limit reached.E15ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E15 error code – Supply or return sensor driftACV documents E15 for the Compact Condens 170, 210, 250 and 300 as: Supply or return sensor drift.E16ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E16 error code – Supply sensor reading stuckACV documents E16 for the Compact Condens 170, 210, 250 and 300 as: Supply sensor reading stuck.E17ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E17 error code – Return sensor reading stuckACV documents E17 for the Compact Condens 170, 210, 250 and 300 as: Return sensor reading stuck.E18ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E18 error code – Supply or return sensor reading changed too rapidlyACV documents E18 for the Compact Condens 170, 210, 250 and 300 as: Supply or return sensor reading…E21ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E21 error code – Internal analogue-to-digital conversion errorACV documents E21 for the Compact Condens 170, 210, 250 and 300 as: Internal analogue-to-digital conversion error.E25ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E25 error code – Internal CRC check errorACV documents E25 for the Compact Condens 170, 210, 250 and 300 as: Internal CRC check error.E30ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E30 error code – Supply sensor short circuitACV documents E30 for the Compact Condens 170, 210, 250 and 300 as: Supply sensor short circuit.E31ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E31 error code – Supply sensor open circuitACV documents E31 for the Compact Condens 170, 210, 250 and 300 as: Supply sensor open circuit.E32ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E32 error code – DHW sensor short circuitACV documents E32 for the Compact Condens 170, 210, 250 and 300 as: DHW sensor short circuit.E33ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E33 error code – DHW sensor open circuitACV documents E33 for the Compact Condens 170, 210, 250 and 300 as: DHW sensor open circuit.E34ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E34 error code – Supply voltage below operating levelACV documents E34 for the Compact Condens 170, 210, 250 and 300 as: Supply voltage below operating level.E37ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E37 error code – Water pressure below 0.7 barACV documents E37 for the Compact Condens 170, 210, 250 and 300 as: Water pressure below 0.7 bar.E43ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E43 error code – Return sensor short circuitACV documents E43 for the Compact Condens 170, 210, 250 and 300 as: Return sensor short circuit.E44ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E44 error code – Return sensor open circuitACV documents E44 for the Compact Condens 170, 210, 250 and 300 as: Return sensor open circuit.E45ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E45 error code – Flue sensor short circuitACV documents E45 for the Compact Condens 170, 210, 250 and 300 as: Flue sensor short circuit.E46ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E46 error code – Flue sensor open circuitACV documents E46 for the Compact Condens 170, 210, 250 and 300 as: Flue sensor open circuit.E47ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E47 error code – Water-pressure sensor disconnected or brokenACV documents E47 for the Compact Condens 170, 210, 250 and 300 as: Water-pressure sensor disconnected or broken.E76ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E76 error code – External automatic-reset limit openedACV documents E76 for the Compact Condens 170, 210, 250 and 300 as: External automatic-reset limit opened.E77ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E77 error code – Siphon switch openACV documents E77 for the Compact Condens 170, 210, 250 and 300 as: Siphon switch open.E80ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E80 error code – Return temperature higher than supplyACV documents E80 for the Compact Condens 170, 210, 250 and 300 as: Return temperature higher than supply.E81ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E81 error code – Supply and return temperatures unequalACV documents E81 for the Compact Condens 170, 210, 250 and 300 as: Supply and return temperatures unequal.E87ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E87 error code – External overtemperature limit openedACV documents E87 for the Compact Condens 170, 210, 250 and 300 as: External overtemperature limit opened.E89ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E89 error code – Parameter outside permitted rangeACV documents E89 for the Compact Condens 170, 210, 250 and 300 as: Parameter outside permitted range.E90ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E90 error code – Controller and display firmware mismatchACV documents E90 for the Compact Condens 170, 210, 250 and 300 as: Controller and display firmware mismatch.E91ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E91 error code – Cascade sensor short circuitACV documents E91 for the Compact Condens 170, 210, 250 and 300 as: Cascade sensor short circuit.E92ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E92 error code – Cascade sensor open circuitACV documents E92 for the Compact Condens 170, 210, 250 and 300 as: Cascade sensor open circuit.E93ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E93 error code – Outdoor sensor short circuitACV documents E93 for the Compact Condens 170, 210, 250 and 300 as: Outdoor sensor short circuit.E94ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E94 error code – Internal display-memory faultACV documents E94 for the Compact Condens 170, 210, 250 and 300 as: Internal display-memory fault.E95ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E95 error code – Invalid cascade supply-sensor readingACV documents E95 for the Compact Condens 170, 210, 250 and 300 as: Invalid cascade supply-sensor reading.E96ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E96 error code – Outdoor sensor open circuitACV documents E96 for the Compact Condens 170, 210, 250 and 300 as: Outdoor sensor open circuit.E97ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E97 error code – Cascade configuration changedACV documents E97 for the Compact Condens 170, 210, 250 and 300 as: Cascade configuration changed.E98ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E98 error code – Cascade bus communication lostACV documents E98 for the Compact Condens 170, 210, 250 and 300 as: Cascade bus communication lost.E99ACV · Compact Condens commercial condensing boiler · EuropeACV Compact Condens E99 error code – Display-to-control-module communication lostACV documents E99 for the Compact Condens 170, 210, 250 and 300 as: Display-to-control-module communication lost.E01ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E01 error code – Ignition failureACV documents E01 for Compact Condens 170, 210, 250 and 300 boilers as “Ignition failure”. The burner did…E02ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E02 error code – False flame detectedACV documents E02 for Compact Condens 170, 210, 250 and 300 boilers as “False flame detected”. A flame…E03ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E03 error code – Boiler overtemperatureACV documents E03 for Compact Condens 170, 210, 250 and 300 boilers as “Boiler overtemperature”. The boiler temperature…E04ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E04 error code – Air-pressure switch zero-position faultACV documents E04 for Compact Condens 170, 210, 250 and 300 boilers as “Air-pressure switch zero-position fault”. The…E05ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E05 error code – Fan speed faultACV documents E05 for Compact Condens 170, 210, 250 and 300 boilers as “Fan speed fault”. The fan…E06ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E06 error code – Airflow or air-pressure switch opened during operationACV documents E06 for Compact Condens 170, 210, 250 and 300 boilers as “Airflow or air-pressure switch opened…E07ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E07 error code – Flue-gas overtemperatureACV documents E07 for Compact Condens 170, 210, 250 and 300 boilers as “Flue-gas overtemperature”. The flue-gas temperature…E08ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E08 error code – Flame-circuit test failureACV documents E08 for Compact Condens 170, 210, 250 and 300 boilers as “Flame-circuit test failure”. The flame-circuit…E09ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E09 error code – Gas-valve circuit test failureACV documents E09 for Compact Condens 170, 210, 250 and 300 boilers as “Gas-valve circuit test failure”. The…E12ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E12 error code – Internal EEPROM configuration faultACV documents E12 for Compact Condens 170, 210, 250 and 300 boilers as “Internal EEPROM configuration fault”. The…E13ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E13 error code – Maximum reset count reachedACV documents E13 for Compact Condens 170, 210, 250 and 300 boilers as “Maximum reset count reached”. The…E15ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E15 error code – Flow or return sensor driftACV documents E15 for Compact Condens 170, 210, 250 and 300 boilers as “Flow or return sensor drift”.…E16ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E16 error code – Flow sensor stuckACV documents E16 for Compact Condens 170, 210, 250 and 300 boilers as “Flow sensor stuck”. The flow-temperature…E17ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E17 error code – Return sensor stuckACV documents E17 for Compact Condens 170, 210, 250 and 300 boilers as “Return sensor stuck”. The return-temperature…E18ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E18 error code – Rapid sensor-value changeACV documents E18 for Compact Condens 170, 210, 250 and 300 boilers as “Rapid sensor-value change”. The flow…E21ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E21 error code – Internal analogue-to-digital conversion faultACV documents E21 for Compact Condens 170, 210, 250 and 300 boilers as “Internal analogue-to-digital conversion fault”. The…E25ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E25 error code – Internal CRC verification faultACV documents E25 for Compact Condens 170, 210, 250 and 300 boilers as “Internal CRC verification fault”. The…E30ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E30 error code – Flow sensor short circuitACV documents E30 for Compact Condens 170, 210, 250 and 300 boilers as “Flow sensor short circuit”. A…E31ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E31 error code – Flow sensor open circuitACV documents E31 for Compact Condens 170, 210, 250 and 300 boilers as “Flow sensor open circuit”. An…E32ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E32 error code – Domestic hot-water sensor short circuitACV documents E32 for Compact Condens 170, 210, 250 and 300 boilers as “Domestic hot-water sensor short circuit”.…E33ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E33 error code – Domestic hot-water sensor open circuitACV documents E33 for Compact Condens 170, 210, 250 and 300 boilers as “Domestic hot-water sensor open circuit”.…E34ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E34 error code – Low mains voltageACV documents E34 for Compact Condens 170, 210, 250 and 300 boilers as “Low mains voltage”. The mains…E37ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E37 error code – Low system water pressureACV documents E37 for Compact Condens 170, 210, 250 and 300 boilers as “Low system water pressure”. System…E43ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E43 error code – Return sensor short circuitACV documents E43 for Compact Condens 170, 210, 250 and 300 boilers as “Return sensor short circuit”. A…E44ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E44 error code – Return sensor open circuitACV documents E44 for Compact Condens 170, 210, 250 and 300 boilers as “Return sensor open circuit”. An…E45ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E45 error code – Flue sensor short circuitACV documents E45 for Compact Condens 170, 210, 250 and 300 boilers as “Flue sensor short circuit”. A…E46ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E46 error code – Flue sensor open circuitACV documents E46 for Compact Condens 170, 210, 250 and 300 boilers as “Flue sensor open circuit”. An…E47ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E47 error code – Water pressure switch faultACV documents E47 for Compact Condens 170, 210, 250 and 300 boilers as “Water pressure switch fault”. The…E76ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E76 error code – External boiler limit openACV documents E76 for Compact Condens 170, 210, 250 and 300 boilers as “External boiler limit open”. An…E77ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E77 error code – Condensate siphon switch openACV documents E77 for Compact Condens 170, 210, 250 and 300 boilers as “Condensate siphon switch open”. The…E80ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E80 error code – Return temperature higher than flowACV documents E80 for Compact Condens 170, 210, 250 and 300 boilers as “Return temperature higher than flow”.…E81ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E81 error code – Flow and return sensor driftACV documents E81 for Compact Condens 170, 210, 250 and 300 boilers as “Flow and return sensor drift”.…E87ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E87 error code – External safety thermostat openACV documents E87 for Compact Condens 170, 210, 250 and 300 boilers as “External safety thermostat open”. An…E89ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E89 error code – Invalid parameter valueACV documents E89 for Compact Condens 170, 210, 250 and 300 boilers as “Invalid parameter value”. One or…E90ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E90 error code – Controller and display firmware incompatibilityACV documents E90 for Compact Condens 170, 210, 250 and 300 boilers as “Controller and display firmware incompatibility”.…E91ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E91 error code – Cascade sensor short circuitACV documents E91 for Compact Condens 170, 210, 250 and 300 boilers as “Cascade sensor short circuit”. A…E92ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E92 error code – Cascade sensor open circuitACV documents E92 for Compact Condens 170, 210, 250 and 300 boilers as “Cascade sensor open circuit”. An…E93ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E93 error code – Outdoor sensor short circuitACV documents E93 for Compact Condens 170, 210, 250 and 300 boilers as “Outdoor sensor short circuit”. A…E94ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E94 error code – Internal display memory faultACV documents E94 for Compact Condens 170, 210, 250 and 300 boilers as “Internal display memory fault”. The…E95ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E95 error code – Invalid cascade heating-flow sensor valueACV documents E95 for Compact Condens 170, 210, 250 and 300 boilers as “Invalid cascade heating-flow sensor value”.…E96ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E96 error code – Outdoor sensor open circuitACV documents E96 for Compact Condens 170, 210, 250 and 300 boilers as “Outdoor sensor open circuit”. An…E97ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E97 error code – Cascade configuration changedACV documents E97 for Compact Condens 170, 210, 250 and 300 boilers as “Cascade configuration changed”. The cascade…E98ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E98 error code – Cascade bus communication lostACV documents E98 for Compact Condens 170, 210, 250 and 300 boilers as “Cascade bus communication lost”. Communication…E99ACV · Compact Condens commercial gas boilers · EuropeACV Compact Condens E99 error code – Control bus communication lostACV documents E99 for Compact Condens 170, 210, 250 and 300 boilers as “Control bus communication lost”. Communication…E00ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E00 error code – Abnormal flame-presence signalACV documents E00 for the HeatMaster 201 MCBA controller as: Abnormal flame-presence signal.E02ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E02 error code – No flame signal after five ignition attemptsACV documents E02 for the HeatMaster 201 MCBA controller as: No flame signal after five ignition attempts.E04ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E04 error code – Volatile controller errorACV documents E04 for the HeatMaster 201 MCBA controller as: Volatile controller error.E11ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E11 error code – EPROM errorACV documents E11 for the HeatMaster 201 MCBA controller as: EPROM error.E12ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E12 error code – Low pressure, low-water safety or 24 V fuse faultACV documents E12 for the HeatMaster 201 MCBA controller as: Low pressure, low-water safety or 24 V fuse…E13ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E13 error code – Internal controller or display errorACV documents E13 for the HeatMaster 201 MCBA controller as: Internal controller or display error.E14ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E14 error code – Internal controller or display errorACV documents E14 for the HeatMaster 201 MCBA controller as: Internal controller or display error.E15ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E15 error code – Internal controller or display errorACV documents E15 for the HeatMaster 201 MCBA controller as: Internal controller or display error.E16ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E16 error code – Internal controller or display errorACV documents E16 for the HeatMaster 201 MCBA controller as: Internal controller or display error.E17ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E17 error code – Internal controller or display errorACV documents E17 for the HeatMaster 201 MCBA controller as: Internal controller or display error.E18ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E18 error code – T1 temperature above 110°CACV documents E18 for the HeatMaster 201 MCBA controller as: T1 temperature above 110°C.E19ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E19 error code – T2 temperature above 110°CACV documents E19 for the HeatMaster 201 MCBA controller as: T2 temperature above 110°C.