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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E25ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E25 error code – T1 temperature gradient too highACV documents E25 for the HeatMaster 201 MCBA controller as: T1 temperature gradient too high.E28ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E28 error code – No fan tachometer signalACV documents E28 for the HeatMaster 201 MCBA controller as: No fan tachometer signal.E31ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E31 error code – NTC1 sensor short circuitACV documents E31 for the HeatMaster 201 MCBA controller as: NTC1 sensor short circuit.E32ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E32 error code – NTC2 sensor short circuitACV documents E32 for the HeatMaster 201 MCBA controller as: NTC2 sensor short circuit.E33ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E33 error code – NTC3 sensor short circuitACV documents E33 for the HeatMaster 201 MCBA controller as: NTC3 sensor short circuit.E36ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E36 error code – NTC1 sensor open circuitACV documents E36 for the HeatMaster 201 MCBA controller as: NTC1 sensor open circuit.E37ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E37 error code – NTC2 sensor open circuitACV documents E37 for the HeatMaster 201 MCBA controller as: NTC2 sensor open circuit.E38ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E38 error code – NTC3 sensor open circuitACV documents E38 for the HeatMaster 201 MCBA controller as: NTC3 sensor open circuit.E44ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E44 error code – Internal controller or display errorACV documents E44 for the HeatMaster 201 MCBA controller as: Internal controller or display error.E60ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E60 error code – Parameter-reading errorACV documents E60 for the HeatMaster 201 MCBA controller as: Parameter-reading error.E65ACV · HeatMaster 201 combined boiler and water heater · EuropeACV HeatMaster 201 E65 error code – Fan power-supply faultACV documents E65 for the HeatMaster 201 MCBA controller as: Fan power-supply fault.E01ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E01 error code – Ignition failureACV documents E01 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Ignition failure”.…E02ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E02 error code – False flame detectedACV documents E02 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “False flame…E03ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E03 error code – Boiler overtemperatureACV documents E03 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Boiler overtemperature”.…E05ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E05 error code – Fan speed faultACV documents E05 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Fan speed…E07ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E07 error code – Flue-gas overtemperatureACV documents E07 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Flue-gas overtemperature”.…E08ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E08 error code – Flame-circuit test failureACV documents E08 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Flame-circuit test…E09ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E09 error code – Gas-valve circuit test failureACV documents E09 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Gas-valve circuit…E12ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E12 error code – Internal EEPROM configuration faultACV documents E12 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Internal EEPROM…E13ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E13 error code – Maximum reset count reachedACV documents E13 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Maximum reset…E15ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E15 error code – Flow or return sensor driftACV documents E15 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Flow or…E16ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E16 error code – Flow sensor stuckACV documents E16 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Flow sensor…E17ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E17 error code – Return sensor stuckACV documents E17 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Return sensor…E18ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E18 error code – Rapid sensor-value changeACV documents E18 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Rapid sensor-value…E19ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E19 error code – Flame failure during start-upACV documents E19 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Flame failure…E21ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E21 error code – Internal analogue-to-digital conversion faultACV documents E21 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Internal analogue-to-digital…E25ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E25 error code – Internal CRC verification faultACV documents E25 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Internal CRC…E30ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E30 error code – Flow sensor short circuitACV documents E30 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Flow sensor…E31ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E31 error code – Flow sensor open circuitACV documents E31 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Flow sensor…E32ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E32 error code – Domestic hot-water sensor short circuitACV documents E32 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Domestic hot-water…E33ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E33 error code – Domestic hot-water sensor open circuitACV documents E33 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Domestic hot-water…E34ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E34 error code – Low mains voltageACV documents E34 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Low mains…E37ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E37 error code – Low system water pressureACV documents E37 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Low system…E43ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E43 error code – Return sensor short circuitACV documents E43 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Return sensor…E44ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E44 error code – Return sensor open circuitACV documents E44 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Return sensor…E45ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E45 error code – Flue sensor short circuitACV documents E45 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Flue sensor…E46ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E46 error code – Flue sensor open circuitACV documents E46 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Flue sensor…E47ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E47 error code – Water pressure switch faultACV documents E47 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Water pressure…E76ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E76 error code – Gas pressure switch or external safety thermostat openACV documents E76 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Gas pressure…E77ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E77 error code – High mixing-valve circuit temperatureACV documents E77 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “High mixing-valve…E78ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E78 error code – Mixing-valve sensor short circuitACV documents E78 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Mixing-valve sensor…E79ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E79 error code – Mixing-valve sensor open circuitACV documents E79 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Mixing-valve sensor…E80ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E80 error code – Return temperature higher than flowACV documents E80 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Return temperature…E81ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E81 error code – Flow and return sensor driftACV documents E81 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Flow and…E82ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E82 error code – Delta-T protection blockACV documents E82 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Delta-T protection…E83ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E83 error code – Delta-T protection lockoutACV documents E83 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Delta-T protection…E85ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E85 error code – Pump speed outside toleranceACV documents E85 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Pump speed…E86ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E86 error code – Pump failureACV documents E86 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Pump failure”.…E87ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E87 error code – External safety thermostat openACV documents E87 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “External safety…E88ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E88 error code – Pump blockedACV documents E88 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Pump blocked”.…E89ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E89 error code – Invalid parameter valueACV documents E89 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Invalid parameter…E90ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E90 error code – Controller and display firmware incompatibilityACV documents E90 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Controller and…E91ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E91 error code – System sensor short circuitACV documents E91 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “System sensor…E92ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E92 error code – System sensor open circuitACV documents E92 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “System sensor…E93ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E93 error code – Outdoor sensor short circuitACV documents E93 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Outdoor sensor…E94ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E94 error code – Internal display memory faultACV documents E94 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Internal display…E95ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E95 error code – Invalid flow sensor valueACV documents E95 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Invalid flow…E96ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E96 error code – Outdoor sensor open circuitACV documents E96 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Outdoor sensor…E97ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E97 error code – Cascade configuration changedACV documents E97 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Cascade configuration…E98ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E98 error code – Cascade bus communication lostACV documents E98 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Cascade bus…E99ACV · HeatMaster 25–120 TC Evo combined boilers and water heaters · EuropeACV HeatMaster TC Evo E99 error code – Control bus communication lostACV documents E99 for HeatMaster 25, 35, 45, 70, 85 and 120 TC Evo appliances as “Control bus…E01ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E01 error code – No flame after five start-up attemptsACV documents E01 for the HeatMaster 25 C as: No flame after five start-up attempts.E02ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E02 error code – Abnormal flame signal detectedACV documents E02 for the HeatMaster 25 C as: Abnormal flame signal detected.E03ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E03 error code – Maximum thermostat open or T1/T2 above 110°CACV documents E03 for the HeatMaster 25 C as: Maximum thermostat open or T1/T2 above 110°C.E05ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E05 error code – No fan tachometer signalACV documents E05 for the HeatMaster 25 C as: No fan tachometer signal.E07ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E07 error code – Flue-gas temperature too high at NTC5ACV documents E07 for the HeatMaster 25 C as: Flue-gas temperature too high at NTC5.E08ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E08 error code – No flame detectedACV documents E08 for the HeatMaster 25 C as: No flame detected.E09ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E09 error code – Gas-valve relay errorACV documents E09 for the HeatMaster 25 C as: Gas-valve relay error.E11ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E11 error code – NTC1 or NTC2 sensor deviationACV documents E11 for the HeatMaster 25 C as: NTC1 or NTC2 sensor deviation.E13ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E13 error code – Remote reset errorACV documents E13 for the HeatMaster 25 C as: Remote reset error.E21ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E21 error code – Analogue-to-digital converter errorACV documents E21 for the HeatMaster 25 C as: Analogue-to-digital converter error.E25ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E25 error code – CRC controller errorACV documents E25 for the HeatMaster 25 C as: CRC controller error.E30ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E30 error code – NTC1 short circuitACV documents E30 for the HeatMaster 25 C as: NTC1 short circuit.E31ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E31 error code – NTC1 open circuitACV documents E31 for the HeatMaster 25 C as: NTC1 open circuit.E32ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E32 error code – NTC3 short circuitACV documents E32 for the HeatMaster 25 C as: NTC3 short circuit.E33ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E33 error code – NTC3 open circuitACV documents E33 for the HeatMaster 25 C as: NTC3 open circuit.E34ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E34 error code – Mains-frequency deviation above 1.5 HzACV documents E34 for the HeatMaster 25 C as: Mains-frequency deviation above 1.5 Hz.E37ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E37 error code – Water-pressure faultACV documents E37 for the HeatMaster 25 C as: Water-pressure fault.E41ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E41 error code – No communication from water-pressure sensorACV documents E41 for the HeatMaster 25 C as: No communication from water-pressure sensor.E43ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E43 error code – NTC2 short circuitACV documents E43 for the HeatMaster 25 C as: NTC2 short circuit.E44ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E44 error code – NTC2 open circuitACV documents E44 for the HeatMaster 25 C as: NTC2 open circuit.E45ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E45 error code – NTC5 short circuitACV documents E45 for the HeatMaster 25 C as: NTC5 short circuit.E46ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E46 error code – NTC5 open circuitACV documents E46 for the HeatMaster 25 C as: NTC5 open circuit.E47ACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C E47 error code – Water-pressure sensor open or defectiveACV documents E47 for the HeatMaster 25 C as: Water-pressure sensor open or defective.NTCACV · HeatMaster 25 C combined boiler and water heater · Europe and United KingdomACV HeatMaster 25 C NTC error code – Maximum T1-to-T2 temperature difference exceededACV documents NTC for the HeatMaster 25 C as: Maximum T1-to-T2 temperature difference exceeded.E01ACV · HeatMaster 25 C condensing boiler and hot-water generator · United Kingdom and EuropeACV HeatMaster 25 C condensing boiler and hot-water generator E01 error code – No flame after five start-up attemptsACV identifies E01 for the HeatMaster 25 C condensing boiler and hot-water generator as: No flame after five…E02ACV · HeatMaster 25 C condensing boiler and hot-water generator · United Kingdom and EuropeACV HeatMaster 25 C condensing boiler and hot-water generator E02 error code – Abnormal flame signal detectedACV identifies E02 for the HeatMaster 25 C condensing boiler and hot-water generator as: Abnormal flame signal detected.E03ACV · HeatMaster 25 C condensing boiler and hot-water generator · United Kingdom and EuropeACV HeatMaster 25 C condensing boiler and hot-water generator E03 error code – Maximum thermostat open or excessive temperatureACV identifies E03 for the HeatMaster 25 C condensing boiler and hot-water generator as: Maximum thermostat open or…E05ACV · HeatMaster 25 C condensing boiler and hot-water generator · United Kingdom and EuropeACV HeatMaster 25 C condensing boiler and hot-water generator E05 error code – No tachometer signal from the fanACV identifies E05 for the HeatMaster 25 C condensing boiler and hot-water generator as: No tachometer signal from…E07ACV · HeatMaster 25 C condensing boiler and hot-water generator · United Kingdom and EuropeACV HeatMaster 25 C condensing boiler and hot-water generator E07 error code – Flue-gas temperature too highACV identifies E07 for the HeatMaster 25 C condensing boiler and hot-water generator as: Flue-gas temperature too high.E08ACV · HeatMaster 25 C condensing boiler and hot-water generator · United Kingdom and EuropeACV HeatMaster 25 C condensing boiler and hot-water generator E08 error code – No flame detectionACV identifies E08 for the HeatMaster 25 C condensing boiler and hot-water generator as: No flame detection.E09ACV · HeatMaster 25 C condensing boiler and hot-water generator · United Kingdom and EuropeACV HeatMaster 25 C condensing boiler and hot-water generator E09 error code – Gas-valve relay errorACV identifies E09 for the HeatMaster 25 C condensing boiler and hot-water generator as: Gas-valve relay error.E11ACV · HeatMaster 25 C condensing boiler and hot-water generator · United Kingdom and EuropeACV HeatMaster 25 C condensing boiler and hot-water generator E11 error code – NTC1 or NTC2 sensor faultACV identifies E11 for the HeatMaster 25 C condensing boiler and hot-water generator as: NTC1 or NTC2 sensor…E13ACV · HeatMaster 25 C condensing boiler and hot-water generator · United Kingdom and EuropeACV HeatMaster 25 C condensing boiler and hot-water generator E13 error code – Remote reset errorACV identifies E13 for the HeatMaster 25 C condensing boiler and hot-water generator as: Remote reset error.E21ACV · HeatMaster 25 C condensing boiler and hot-water generator · United Kingdom and EuropeACV HeatMaster 25 C condensing boiler and hot-water generator E21 error code – ADC controller errorACV identifies E21 for the HeatMaster 25 C condensing boiler and hot-water generator as: ADC controller error.E25ACV · HeatMaster 25 C condensing boiler and hot-water generator · United Kingdom and EuropeACV HeatMaster 25 C condensing boiler and hot-water generator E25 error code – CRC controller errorACV identifies E25 for the HeatMaster 25 C condensing boiler and hot-water generator as: CRC controller error.E30ACV · HeatMaster 25 C condensing boiler and hot-water generator · United Kingdom and EuropeACV HeatMaster 25 C condensing boiler and hot-water generator E30 error code – NTC1 short circuitACV identifies E30 for the HeatMaster 25 C condensing boiler and hot-water generator as: NTC1 short circuit.E31ACV · HeatMaster 25 C condensing boiler and hot-water generator · United Kingdom and EuropeACV HeatMaster 25 C condensing boiler and hot-water generator E31 error code – NTC1 open circuitACV identifies E31 for the HeatMaster 25 C condensing boiler and hot-water generator as: NTC1 open circuit.E32ACV · HeatMaster 25 C condensing boiler and hot-water generator · United Kingdom and EuropeACV HeatMaster 25 C condensing boiler and hot-water generator E32 error code – NTC3 short circuitACV identifies E32 for the HeatMaster 25 C condensing boiler and hot-water generator as: NTC3 short circuit.E33ACV · HeatMaster 25 C condensing boiler and hot-water generator · United Kingdom and EuropeACV HeatMaster 25 C condensing boiler and hot-water generator E33 error code – NTC3 open circuitACV identifies E33 for the HeatMaster 25 C condensing boiler and hot-water generator as: NTC3 open circuit.