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Keston error codes

Find the meaning of Keston fault, warning and status codes, with model context, documented causes, safe checks and links to available manufacturer guidance.

444documented codes
20products and models
1product categories

About Keston error codes

An error code is a diagnostic clue, not a complete repair diagnosis. Keston may reuse similar-looking codes across different products, model generations or regions, so always confirm the complete code and exact model before following instructions or ordering parts.

This profile connects every indexed Keston code to its dedicated explanation page. Each page is structured around the search intent: a quick meaning, symptoms, likely causes, safe troubleshooting, reset guidance, applicable products and the point at which professional help is appropriate. Records marked as verified include the manufacturer or another authoritative technical source.

Start with the code shown on the display, then narrow the result by product or model. Do not assume that a reset has repaired the underlying fault. If a code returns, the product is unsafe, or diagnosis requires internal electrical, gas, refrigerant or moving components, stop and use an authorised technician.

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E30Keston · Keston C90 and C110 condensing boilers · United Kingdom and IrelandE30 – Keston C90/C110 error codeKeston documents E30 for C90 and C110 boiler modules as “Flow/return temperature difference too high”. The manual classifies…E31Keston · Keston C90 and C110 condensing boilers · United Kingdom and IrelandE31 – Keston C90/C110 error codeKeston documents E31 for C90 and C110 boiler modules as “Flow thermistor short circuit”. The manual classifies it…E32Keston · Keston C90 and C110 condensing boilers · United Kingdom and IrelandE32 – Keston C90/C110 error codeKeston documents E32 for C90 and C110 boiler modules as “Return thermistor short circuit”. The manual classifies it…E36Keston · Keston C90 and C110 condensing boilers · United Kingdom and IrelandE36 – Keston C90/C110 error codeKeston documents E36 for C90 and C110 boiler modules as “Flow thermistor open circuit”. The manual classifies it…E37Keston · Keston C90 and C110 condensing boilers · United Kingdom and IrelandE37 – Keston C90/C110 error codeKeston documents E37 for C90 and C110 boiler modules as “Return thermistor open circuit”. The manual classifies it…E44Keston · Keston C90 and C110 condensing boilers · United Kingdom and IrelandE44 – Keston C90/C110 error codeKeston documents E44 for C90 and C110 boiler modules as “Low water pressure”. The manual classifies it as…LOCKOUT 15 FLASHESKeston · Keston Celsius 25 and 25P condensing boilers · United Kingdom and IrelandLOCKOUT 15 FLASHES – Control PCB faultKeston identifies the Celsius 25/25P diagnostic pattern LOCKOUT 15 FLASHES as “Control PCB fault”. This boiler has no…LOCKOUT 1 FLASH + DIAG 1Keston · Keston Celsius 25 and 25P condensing boilers · United Kingdom and IrelandLOCKOUT 1 FLASH + DIAG 1 – Flow overheat thermostat activatedKeston identifies the Celsius 25/25P diagnostic pattern LOCKOUT 1 FLASH + DIAG 1 as “Flow overheat thermostat activated”.…LOCKOUT 1 FLASH + DIAG 2Keston · Keston Celsius 25 and 25P condensing boilers · United Kingdom and IrelandLOCKOUT 1 FLASH + DIAG 2 – Cabinet overheatKeston identifies the Celsius 25/25P diagnostic pattern LOCKOUT 1 FLASH + DIAG 2 as “Cabinet overheat”. This boiler…LOCKOUT 1 FLASH + DIAG 3Keston · Keston Celsius 25 and 25P condensing boilers · United Kingdom and IrelandLOCKOUT 1 FLASH + DIAG 3 – Flue overheatKeston identifies the Celsius 25/25P diagnostic pattern LOCKOUT 1 FLASH + DIAG 3 as “Flue overheat”. This boiler…LOCKOUT 1 FLASH + DIAG 4Keston · Keston Celsius 25 and 25P condensing boilers · United Kingdom and IrelandLOCKOUT 1 FLASH + DIAG 4 – Spare sensor connection or wiring-loom faultKeston identifies the Celsius 25/25P diagnostic pattern LOCKOUT 1 FLASH + DIAG 4 as “Spare sensor connection or…LOCKOUT 2 FLASHES + DIAG 1Keston · Keston Celsius 25 and 25P condensing boilers · United Kingdom and IrelandLOCKOUT 2 FLASHES + DIAG 1 – Ignition failure after five attemptsKeston identifies the Celsius 25/25P diagnostic pattern LOCKOUT 2 FLASHES + DIAG 1 as “Ignition failure after five…LOCKOUT 2 FLASHES + DIAG 2Keston · Keston Celsius 25 and 25P condensing boilers · United Kingdom and IrelandLOCKOUT 2 FLASHES + DIAG 2 – Flame lost while runningKeston identifies the Celsius 25/25P diagnostic pattern LOCKOUT 2 FLASHES + DIAG 2 as “Flame lost while running”.…LOCKOUT 3 FLASHES + DIAG 1Keston · Keston Celsius 25 and 25P condensing boilers · United Kingdom and IrelandLOCKOUT 3 FLASHES + DIAG 1 – Flow thermistor disconnected or faultyKeston identifies the Celsius 25/25P diagnostic pattern LOCKOUT 3 FLASHES + DIAG 1 as “Flow thermistor disconnected or…LOCKOUT 3 FLASHES + DIAG 2Keston · Keston Celsius 25 and 25P condensing boilers · United Kingdom and IrelandLOCKOUT 3 FLASHES + DIAG 2 – Return thermistor disconnected or faultyKeston identifies the Celsius 25/25P diagnostic pattern LOCKOUT 3 FLASHES + DIAG 2 as “Return thermistor disconnected or…LOCKOUT 4 FLASHESKeston · Keston Celsius 25 and 25P condensing boilers · United Kingdom and IrelandLOCKOUT 4 FLASHES – Low water pressureKeston identifies the Celsius 25/25P diagnostic pattern LOCKOUT 4 FLASHES as “Low water pressure”. This boiler has no…LOCKOUT 5 FLASHESKeston · Keston Celsius 25 and 25P condensing boilers · United Kingdom and IrelandLOCKOUT 5 FLASHES – Fan speed below 500 rpmKeston identifies the Celsius 25/25P diagnostic pattern LOCKOUT 5 FLASHES as “Fan speed below 500 rpm”. This boiler…LOCKOUT LED CONSTANT FLASHKeston · Keston Celsius 25 and 25P condensing boilers · United Kingdom and IrelandLOCKOUT LED CONSTANT FLASH – Fan PCB faultKeston identifies the Celsius 25/25P diagnostic pattern LOCKOUT LED CONSTANT FLASH as “Fan PCB fault”. This boiler has…MAINS LED OFFKeston · Keston Celsius 25 and 25P condensing boilers · United Kingdom and IrelandMAINS LED OFF – No mains powerKeston identifies the Celsius 25/25P diagnostic pattern MAINS LED OFF as “No mains power”. This boiler has no…MAINS LED RAPID FLASHKeston · Keston Celsius 25 and 25P condensing boilers · United Kingdom and IrelandMAINS LED RAPID FLASH – Boiler off at user controlKeston identifies the Celsius 25/25P diagnostic pattern MAINS LED RAPID FLASH as “Boiler off at user control”. This…MAINS LED SLOW FLASHKeston · Keston Celsius 25 and 25P condensing boilers · United Kingdom and IrelandMAINS LED SLOW FLASH – External controls are not calling for heatKeston identifies the Celsius 25/25P diagnostic pattern MAINS LED SLOW FLASH as “External controls are not calling for…FAN FAULTKeston · Keston Combi C30 and C35 combination boilers · United Kingdom and IrelandFAN FAULT – Keston Combi C30/C35 faultKeston documents the display message “FAN FAULT” for the 2018 Combi C30 and C35 range as combustion fan…FLAME LOSSKeston · Keston Combi C30 and C35 combination boilers · United Kingdom and IrelandFLAME LOSS – Keston Combi C30/C35 faultKeston documents the display message “FLAME LOSS” for the 2018 Combi C30 and C35 range as flame lost…FLAME ON BEFORE GAS ONKeston · Keston Combi C30 and C35 combination boilers · United Kingdom and IrelandFLAME ON BEFORE GAS ON – Keston Combi C30/C35 faultKeston documents the display message “FLAME ON BEFORE GAS ON” for the 2018 Combi C30 and C35 range…FLOW THERMISTOR FAULTKeston · Keston Combi C30 and C35 combination boilers · United Kingdom and IrelandFLOW THERMISTOR FAULT – Keston Combi C30/C35 faultKeston documents the display message “FLOW THERMISTOR FAULT” for the 2018 Combi C30 and C35 range as flow-temperature…IGNITION LOCKOUTKeston · Keston Combi C30 and C35 combination boilers · United Kingdom and IrelandIGNITION LOCKOUT – Keston Combi C30/C35 faultKeston documents the display message “IGNITION LOCKOUT” for the 2018 Combi C30 and C35 range as ignition failed…LOW MAINS VOLTAGEKeston · Keston Combi C30 and C35 combination boilers · United Kingdom and IrelandLOW MAINS VOLTAGE – Keston Combi C30/C35 faultKeston documents the display message “LOW MAINS VOLTAGE” for the 2018 Combi C30 and C35 range as incoming…OUTSIDE SENSOR FAULTKeston · Keston Combi C30 and C35 combination boilers · United Kingdom and IrelandOUTSIDE SENSOR FAULT – Keston Combi C30/C35 faultKeston documents the display message “OUTSIDE SENSOR FAULT” for the 2018 Combi C30 and C35 range as outside-temperature…OVERHEAT LOCKOUTKeston · Keston Combi C30 and C35 combination boilers · United Kingdom and IrelandOVERHEAT LOCKOUT – Keston Combi C30/C35 faultKeston documents the display message “OVERHEAT LOCKOUT” for the 2018 Combi C30 and C35 range as boiler overheat…PCB FAULTKeston · Keston Combi C30 and C35 combination boilers · United Kingdom and IrelandPCB FAULT – Keston Combi C30/C35 faultKeston documents the display message “PCB FAULT” for the 2018 Combi C30 and C35 range as printed circuit…RETURN THERMISTOR FAULTKeston · Keston Combi C30 and C35 combination boilers · United Kingdom and IrelandRETURN THERMISTOR FAULT – Keston Combi C30/C35 faultKeston documents the display message “RETURN THERMISTOR FAULT” for the 2018 Combi C30 and C35 range as return-temperature…TOO MANY RESTARTSKeston · Keston Combi C30 and C35 combination boilers · United Kingdom and IrelandTOO MANY RESTARTS – Keston Combi C30/C35 faultKeston documents the display message “TOO MANY RESTARTS” for the 2018 Combi C30 and C35 range as too…WATER PRESSUREKeston · Keston Combi C30 and C35 combination boilers · United Kingdom and IrelandWATER PRESSURE – Keston Combi C30/C35 faultKeston documents the display message “WATER PRESSURE” for the 2018 Combi C30 and C35 range as system water-pressure…Blocked Flue/CondensateKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandBlocked Flue/Condensate – Keston Combi² error messageKeston documents “Blocked Flue/Condensate” on the Combi² C30 and C35 as the boiler has detected a flue restriction…DHW Thermistor FaultKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandDHW Thermistor Fault – Keston Combi² error messageKeston documents “DHW Thermistor Fault” on the Combi² C30 and C35 as domestic-hot-water temperature sensor or circuit fault.…Fan FaultKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandFan Fault – Keston Combi² error messageKeston documents “Fan Fault” on the Combi² C30 and C35 as combustion fan or fan-control fault. This is…Flame LossKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandFlame Loss – Keston Combi² error messageKeston documents “Flame Loss” on the Combi² C30 and C35 as the burner flame was lost during operation.…Flame On Before Gas OnKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandFlame On Before Gas On – Keston Combi² error messageKeston documents “Flame On Before Gas On” on the Combi² C30 and C35 as a flame signal was…Flow Thermistor FaultKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandFlow Thermistor Fault – Keston Combi² error messageKeston documents “Flow Thermistor Fault” on the Combi² C30 and C35 as flow-temperature sensor or circuit fault. This…Gas Valve FaultKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandGas Valve Fault – Keston Combi² error messageKeston documents “Gas Valve Fault” on the Combi² C30 and C35 as gas-valve control or electrical-supply fault. This…Ignition LockoutKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandIgnition Lockout – Keston Combi² error messageKeston documents “Ignition Lockout” on the Combi² C30 and C35 as ignition attempts did not establish a safe…Low Mains VoltageKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandLow Mains Voltage – Keston Combi² error messageKeston documents “Low Mains Voltage” on the Combi² C30 and C35 as incoming mains voltage is below the…Low Water PressureKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandLow Water Pressure – Keston Combi² error messageKeston documents “Low Water Pressure” on the Combi² C30 and C35 as heating-system pressure is below the permitted…No Water FlowKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandNo Water Flow – Keston Combi² error messageKeston documents “No Water Flow” on the Combi² C30 and C35 as adequate heating-water circulation was not detected.…Outside Sensor FaultKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandOutside Sensor Fault – Keston Combi² error messageKeston documents “Outside Sensor Fault” on the Combi² C30 and C35 as outside-temperature sensor or circuit fault. This…OverheatKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandOverheat – Keston Combi² error messageKeston documents “Overheat” on the Combi² C30 and C35 as boiler overheat condition. This is the 2023 Combi²…PCB FaultKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandPCB Fault – Keston Combi² error messageKeston documents “PCB Fault” on the Combi² C30 and C35 as boiler printed-circuit-board fault. This is the 2023…Pump Dry RunKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandPump Dry Run – Keston Combi² error messageKeston documents “Pump Dry Run” on the Combi² C30 and C35 as the pump has detected dry-running conditions.…Pump FaultKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandPump Fault – Keston Combi² error messageKeston documents “Pump Fault” on the Combi² C30 and C35 as the boiler pump or its feedback circuit…Pump Rotor BlockedKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandPump Rotor Blocked – Keston Combi² error messageKeston documents “Pump Rotor Blocked” on the Combi² C30 and C35 as the boiler pump rotor is blocked.…Return Thermistor FaultKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandReturn Thermistor Fault – Keston Combi² error messageKeston documents “Return Thermistor Fault” on the Combi² C30 and C35 as return-temperature sensor or circuit fault. This…Room Thermostat FaultKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandRoom Thermostat Fault – Keston Combi² error messageKeston documents “Room Thermostat Fault” on the Combi² C30 and C35 as room thermostat communication, power or demand…Spare PCB Not SetKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandSpare PCB Not Set – Keston Combi² error messageKeston documents “Spare PCB Not Set” on the Combi² C30 and C35 as a replacement pcb has not…Too Many RestartsKeston · Keston Combi² C30 and C35 combination boilers · United Kingdom and IrelandToo Many Restarts – Keston Combi² error messageKeston documents “Too Many Restarts” on the Combi² C30 and C35 as the control has recorded excessive restart…BLOCKED FLUE CONDENSATEKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandBLOCKED FLUE CONDENSATE – Keston Combi² C30/C35 error codeKeston documents “Blocked flue or condensate” for the Combi² C30 and C35. This display message identifies a boiler-detected…DHW THERMISTOR FAULTKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandDHW THERMISTOR FAULT – Keston Combi² C30/C35 error codeKeston documents “Domestic-hot-water thermistor fault” for the Combi² C30 and C35. This display message identifies a boiler-detected fault…FAN FAULTKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandFAN FAULT – Keston Combi² C30/C35 error codeKeston documents “Fan fault” for the Combi² C30 and C35. This display message identifies a boiler-detected fault or…FLAME LOSSKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandFLAME LOSS – Keston Combi² C30/C35 error codeKeston documents “Flame loss” for the Combi² C30 and C35. This display message identifies a boiler-detected fault or…FLAME ON BEFORE GAS ONKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandFLAME ON BEFORE GAS ON – Keston Combi² C30/C35 error codeKeston documents “Flame detected before gas command” for the Combi² C30 and C35. This display message identifies a…FLOW THERMISTOR FAULTKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandFLOW THERMISTOR FAULT – Keston Combi² C30/C35 error codeKeston documents “Flow thermistor fault” for the Combi² C30 and C35. This display message identifies a boiler-detected fault…GAS VALVE FAULTKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandGAS VALVE FAULT – Keston Combi² C30/C35 error codeKeston documents “Gas valve fault” for the Combi² C30 and C35. This display message identifies a boiler-detected fault…IGNITION LOCKOUTKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandIGNITION LOCKOUT – Keston Combi² C30/C35 error codeKeston documents “Ignition lockout” for the Combi² C30 and C35. This display message identifies a boiler-detected fault or…LOW MAINS VOLTAGEKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandLOW MAINS VOLTAGE – Keston Combi² C30/C35 error codeKeston documents “Low mains voltage” for the Combi² C30 and C35. This display message identifies a boiler-detected fault…LOW WATER PRESSUREKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandLOW WATER PRESSURE – Keston Combi² C30/C35 error codeKeston documents “Low system water pressure” for the Combi² C30 and C35. This display message identifies a boiler-detected…NO WATER FLOWKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandNO WATER FLOW – Keston Combi² C30/C35 error codeKeston documents “No water flow” for the Combi² C30 and C35. This display message identifies a boiler-detected fault…OUTSIDE SENSOR FAULTKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandOUTSIDE SENSOR FAULT – Keston Combi² C30/C35 error codeKeston documents “Outside sensor fault” for the Combi² C30 and C35. This display message identifies a boiler-detected fault…OVERHEATKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandOVERHEAT – Keston Combi² C30/C35 error codeKeston documents “Overheat lockout” for the Combi² C30 and C35. This display message identifies a boiler-detected fault or…PCB FAULTKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandPCB FAULT – Keston Combi² C30/C35 error codeKeston documents “Printed circuit board fault” for the Combi² C30 and C35. This display message identifies a boiler-detected…PUMP DRY RUNKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandPUMP DRY RUN – Keston Combi² C30/C35 error codeKeston documents “Pump dry-run protection” for the Combi² C30 and C35. This display message identifies a boiler-detected fault…PUMP FAULTKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandPUMP FAULT – Keston Combi² C30/C35 error codeKeston documents “Pump fault” for the Combi² C30 and C35. This display message identifies a boiler-detected fault or…PUMP ROTOR BLOCKEDKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandPUMP ROTOR BLOCKED – Keston Combi² C30/C35 error codeKeston documents “Pump rotor blocked” for the Combi² C30 and C35. This display message identifies a boiler-detected fault…RETURN THERMISTOR FAULTKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandRETURN THERMISTOR FAULT – Keston Combi² C30/C35 error codeKeston documents “Return thermistor fault” for the Combi² C30 and C35. This display message identifies a boiler-detected fault…ROOM THERMOSTAT FAULTKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandROOM THERMOSTAT FAULT – Keston Combi² C30/C35 error codeKeston documents “Room thermostat fault” for the Combi² C30 and C35. This display message identifies a boiler-detected fault…SPARE PCB NOT SETKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandSPARE PCB NOT SET – Keston Combi² C30/C35 error codeKeston documents “Replacement PCB not configured” for the Combi² C30 and C35. This display message identifies a boiler-detected…TOO MANY RESTARTSKeston · Keston Combi² C30 and C35 gas boilers · United Kingdom and IrelandTOO MANY RESTARTS – Keston Combi² C30/C35 error codeKeston documents “Too many restarts” for the Combi² C30 and C35. This display message identifies a boiler-detected fault…BCC FaultKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaBCC Fault – Keston Heat 45/55 error messageKeston documents “BCC Fault” for Heat 45, 55, 45P and 55P boilers as a fault condition in which…Cylinder Thermistor FaultKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaCylinder Thermistor Fault – Keston Heat 45/55 error messageKeston documents “Cylinder Thermistor Fault” for Heat 45, 55, 45P and 55P boilers as a fault condition in…External Interlock OffKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaExternal Interlock Off – Keston Heat 45/55 error messageKeston documents “External Interlock Off” for Heat 45, 55, 45P and 55P boilers as a fault condition in…False Flame LockoutKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaFalse Flame Lockout – Keston Heat 45/55 error messageKeston documents “False Flame Lockout” for Heat 45, 55, 45P and 55P boilers as a fault condition in…Fan FaultKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaFan Fault – Keston Heat 45/55 error messageKeston documents “Fan Fault” for Heat 45, 55, 45P and 55P boilers as a fault condition in which…Flame LossKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaFlame Loss – Keston Heat 45/55 error messageKeston documents “Flame Loss” for Heat 45, 55, 45P and 55P boilers as a fault condition in which…Flow/Return ReversedKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaFlow/Return Reversed – Keston Heat 45/55 error messageKeston documents “Flow/Return Reversed” for Heat 45, 55, 45P and 55P boilers as a fault condition in which…Flow Thermistor FaultKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaFlow Thermistor Fault – Keston Heat 45/55 error messageKeston documents “Flow Thermistor Fault” for Heat 45, 55, 45P and 55P boilers as a fault condition in…Flue Thermistor FaultKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaFlue Thermistor Fault – Keston Heat 45/55 error messageKeston documents “Flue Thermistor Fault” for Heat 45, 55, 45P and 55P boilers as a fault condition in…Ignition LockoutKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaIgnition Lockout – Keston Heat 45/55 error messageKeston documents “Ignition Lockout” for Heat 45, 55, 45P and 55P boilers as a fault condition in which…Low Mains VoltageKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaLow Mains Voltage – Keston Heat 45/55 error messageKeston documents “Low Mains Voltage” for Heat 45, 55, 45P and 55P boilers as a fault condition in…Low Water PressureKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaLow Water Pressure – Keston Heat 45/55 error messageKeston documents “Low Water Pressure” for Heat 45, 55, 45P and 55P boilers as a fault condition in…Outside Sensor FaultKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaOutside Sensor Fault – Keston Heat 45/55 error messageKeston documents “Outside Sensor Fault” for Heat 45, 55, 45P and 55P boilers as a fault condition in…Overheat LockoutKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaOverheat Lockout – Keston Heat 45/55 error messageKeston documents “Overheat Lockout” for Heat 45, 55, 45P and 55P boilers as a fault condition in which…PCB FaultKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaPCB Fault – Keston Heat 45/55 error messageKeston documents “PCB Fault” for Heat 45, 55, 45P and 55P boilers as a fault condition in which…Return Thermistor FaultKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaReturn Thermistor Fault – Keston Heat 45/55 error messageKeston documents “Return Thermistor Fault” for Heat 45, 55, 45P and 55P boilers as a fault condition in…Too Many ResetsKeston · Keston Heat 45, 55, 45P and 55P boilers · United Kingdom, Ireland and RomaniaToo Many Resets – Keston Heat 45/55 error messageKeston documents “Too Many Resets” for Heat 45, 55, 45P and 55P boilers as a fault condition in…01Keston · Keston Heat² 45, 55, 45P and 55P boilers · United Kingdom, Ireland and Romania01 – Keston Heat² error codeKeston identifies OpenTherm fault 01 on Heat² 45, 55, 45P and 55P boilers as “Flow thermistor open circuit”.…02Keston · Keston Heat² 45, 55, 45P and 55P boilers · United Kingdom, Ireland and Romania02 – Keston Heat² error codeKeston identifies OpenTherm fault 02 on Heat² 45, 55, 45P and 55P boilers as “Flow thermistor short circuit”.…03Keston · Keston Heat² 45, 55, 45P and 55P boilers · United Kingdom, Ireland and Romania03 – Keston Heat² error codeKeston identifies OpenTherm fault 03 on Heat² 45, 55, 45P and 55P boilers as “Return thermistor open circuit”.…04Keston · Keston Heat² 45, 55, 45P and 55P boilers · United Kingdom, Ireland and Romania04 – Keston Heat² error codeKeston identifies OpenTherm fault 04 on Heat² 45, 55, 45P and 55P boilers as “Return thermistor short circuit”.…05Keston · Keston Heat² 45, 55, 45P and 55P boilers · United Kingdom, Ireland and Romania05 – Keston Heat² error codeKeston identifies OpenTherm fault 05 on Heat² 45, 55, 45P and 55P boilers as “Flue thermistor open circuit”.…06Keston · Keston Heat² 45, 55, 45P and 55P boilers · United Kingdom, Ireland and Romania06 – Keston Heat² error codeKeston identifies OpenTherm fault 06 on Heat² 45, 55, 45P and 55P boilers as “Flue thermistor short circuit”.…07Keston · Keston Heat² 45, 55, 45P and 55P boilers · United Kingdom, Ireland and Romania07 – Keston Heat² error codeKeston identifies OpenTherm fault 07 on Heat² 45, 55, 45P and 55P boilers as “DHW thermistor open circuit”.…08Keston · Keston Heat² 45, 55, 45P and 55P boilers · United Kingdom, Ireland and Romania08 – Keston Heat² error codeKeston identifies OpenTherm fault 08 on Heat² 45, 55, 45P and 55P boilers as “DHW thermistor short circuit”.…