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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Popular Keston codes
Lockout LED constant flashKeston · Celsius 25 and 25P boilers · United KingdomLockout LED constant flash — Fan PCB faultA constantly flashing red lockout indicator is identified by the manual as a fan-control PCB fault.Lockout 15 flashesKeston · Celsius 25 and 25P boilers · United KingdomLockout 15 flashes — Control PCB faultA repeating sequence of fifteen red lockout flashes followed by a pause indicates a control-board fault that does…Lockout 5 flashesKeston · Celsius 25 and 25P boilers · United KingdomLockout 5 flashes — Fan-speed failureFive red lockout flashes every two seconds indicate that fan speed has fallen below the required operating threshold.Lockout 4 flashesKeston · Celsius 25 and 25P boilers · United KingdomLockout 4 flashes — Low system-water pressureFour red lockout flashes every two seconds indicate that the boiler has detected insufficient system-water pressure.Lockout 3 flashes + LED 2Keston · Celsius 25 and 25P boilers · United KingdomLockout 3 flashes + LED 2 — Return thermistor disconnected or faultyThree red lockout flashes with diagnostic LED 2 illuminated identify a return-temperature thermistor circuit fault.Lockout 3 flashes + LED 1Keston · Celsius 25 and 25P boilers · United KingdomLockout 3 flashes + LED 1 — Flow thermistor disconnected or faultyThree red lockout flashes with diagnostic LED 1 illuminated identify a flow-temperature thermistor circuit fault.Lockout 2 flashes + LED 2Keston · Celsius 25 and 25P boilers · United KingdomLockout 2 flashes + LED 2 — Flame lost while runningTwo red lockout flashes with diagnostic LED 2 illuminated mean the boiler established a flame but lost it…Lockout 2 flashes + LED 1Keston · Celsius 25 and 25P boilers · United KingdomLockout 2 flashes + LED 1 — Ignition failureTwo red lockout flashes with diagnostic LED 1 illuminated mean the boiler has attempted to ignite repeatedly without…
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38Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania38 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 38 for the Heat² 45, 55, 45P and 55P as “Flow-to-return delta-temperature blocking”.…39Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania39 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 39 for the Heat² 45, 55, 45P and 55P as “Flow overheat lockout”.…40Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania40 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 40 for the Heat² 45, 55, 45P and 55P as “Return overheat lockout”.…41Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania41 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 41 for the Heat² 45, 55, 45P and 55P as “Flue overheat or…42Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania42 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 42 for the Heat² 45, 55, 45P and 55P as “Heat-exchanger overheat blocking”.…50Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania50 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 50 for the Heat² 45, 55, 45P and 55P as “No central-heating water…51Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania51 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 51 for the Heat² 45, 55, 45P and 55P as “Low water pressure”.…52Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania52 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 52 for the Heat² 45, 55, 45P and 55P as “No flame signal…53Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania53 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 53 for the Heat² 45, 55, 45P and 55P as “Flame loss during…54Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania54 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 54 for the Heat² 45, 55, 45P and 55P as “Flame loss during…55Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania55 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 55 for the Heat² 45, 55, 45P and 55P as “Flame loss during…56Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania56 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 56 for the Heat² 45, 55, 45P and 55P as “Flame loss during…57Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania57 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 57 for the Heat² 45, 55, 45P and 55P as “False flame with…58Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania58 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 58 for the Heat² 45, 55, 45P and 55P as “No flame after…59Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania59 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 59 for the Heat² 45, 55, 45P and 55P as “Fan-speed standstill check…60Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania60 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 60 for the Heat² 45, 55, 45P and 55P as “Fan speed not…61Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania61 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 61 for the Heat² 45, 55, 45P and 55P as “Fan-speed error during…62Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania62 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 62 for the Heat² 45, 55, 45P and 55P as “Fan-speed minimum or…63Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania63 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 63 for the Heat² 45, 55, 45P and 55P as “Mains overvoltage warning”.…64Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania64 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 64 for the Heat² 45, 55, 45P and 55P as “Mains undervoltage blocking”.…65Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania65 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 65 for the Heat² 45, 55, 45P and 55P as “OpenTherm Plus communication…66Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania66 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 66 for the Heat² 45, 55, 45P and 55P as “Too many remote…67Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania67 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 67 for the Heat² 45, 55, 45P and 55P as “No water-flow indication”.…68Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania68 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 68 for the Heat² 45, 55, 45P and 55P as “PWM pump blocking…69Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania69 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 69 for the Heat² 45, 55, 45P and 55P as “PWM pump electrical…70Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania70 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 70 for the Heat² 45, 55, 45P and 55P as “Heat-exchanger water-flow fault…71Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania71 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 71 for the Heat² 45, 55, 45P and 55P as “PWM pump dry-run…72Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania72 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 72 for the Heat² 45, 55, 45P and 55P as “Pump warning code;…73Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania73 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 73 for the Heat² 45, 55, 45P and 55P as “VariCAN communication error”.…74Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania74 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 74 for the Heat² 45, 55, 45P and 55P as “Safety interlock function…75Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania75 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 75 for the Heat² 45, 55, 45P and 55P as “Air-pressure-switch error”. The…76Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania76 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 76 for the Heat² 45, 55, 45P and 55P as “Air-pressure-switch warning; restart”.…77Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania77 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 77 for the Heat² 45, 55, 45P and 55P as “High water pressure”.…78Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania78 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 78 for the Heat² 45, 55, 45P and 55P as “Minimum water-flow-rate fault”.…79Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania79 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 79 for the Heat² 45, 55, 45P and 55P as “Maximum water-flow rate…80Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania80 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 80 for the Heat² 45, 55, 45P and 55P as “Quartz crystal error”.…81Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania81 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 81 for the Heat² 45, 55, 45P and 55P as “0–10 V input…93Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania93 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 93 for the Heat² 45, 55, 45P and 55P as “Retails supervision error…94Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania94 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 94 for the Heat² 45, 55, 45P and 55P as “Controller requests re-update”.…95Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania95 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 95 for the Heat² 45, 55, 45P and 55P as “Programming mode blocking”.…96Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania96 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 96 for the Heat² 45, 55, 45P and 55P as “Parameter mismatch lockout”.…97Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania97 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 97 for the Heat² 45, 55, 45P and 55P as “Parameter-set lockout”. The…98Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania98 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 98 for the Heat² 45, 55, 45P and 55P as “Internal blocking error”.…99Keston · Keston Heat² 45 and 55 commercial boilers · United Kingdom, Ireland and Romania99 – Keston Heat² 45/55 error codeKeston documents OpenTherm error code 99 for the Heat² 45, 55, 45P and 55P as “Internal system lockout”.…E01Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE01 – Flame sequence lockoutKeston documents E01 for the Qudos 28h and Qudos 28hP as “Flame sequence lockout”. Match the code to…E02Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE02 – Ignition failure after five attemptsKeston documents E02 for the Qudos 28h and Qudos 28hP as “Ignition failure after five attempts”. Match the…E03Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE03 – Spark gap too small or gas valve faultKeston documents E03 for the Qudos 28h and Qudos 28hP as “Spark gap too small or gas valve…E04Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE04 – Flame lost five times during one demandKeston documents E04 for the Qudos 28h and Qudos 28hP as “Flame lost five times during one demand”.…E12Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE12 – Flow overheatKeston documents E12 for the Qudos 28h and Qudos 28hP as “Flow overheat”. Match the code to this…E20Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE20 – Fan unable to reach ignition speedKeston documents E20 for the Qudos 28h and Qudos 28hP as “Fan unable to reach ignition speed”. Match…E24Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE24 – Return temperature exceeds flow temperature by 10°CKeston documents E24 for the Qudos 28h and Qudos 28hP as “Return temperature exceeds flow temperature by 10°C”.…E25Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE25 – Flow temperature increased too quicklyKeston documents E25 for the Qudos 28h and Qudos 28hP as “Flow temperature increased too quickly”. Match the…E26Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE26 – Water pressure sensor open circuit or disconnectedKeston documents E26 for the Qudos 28h and Qudos 28hP as “Water pressure sensor open circuit or disconnected”.…E28Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE28 – Fan faultKeston documents E28 for the Qudos 28h and Qudos 28hP as “Fan fault”. Match the code to this…E31Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE31 – Flow thermistor short circuitKeston documents E31 for the Qudos 28h and Qudos 28hP as “Flow thermistor short circuit”. Match the code…E32Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE32 – Return thermistor short circuitKeston documents E32 for the Qudos 28h and Qudos 28hP as “Return thermistor short circuit”. Match the code…E33Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE33 – DHW thermistor short circuitKeston documents E33 for the Qudos 28h and Qudos 28hP as “DHW thermistor short circuit”. Match the code…E35Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE35 – Flue thermistor short circuitKeston documents E35 for the Qudos 28h and Qudos 28hP as “Flue thermistor short circuit”. Match the code…E36Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE36 – Flow thermistor open circuit or disconnectedKeston documents E36 for the Qudos 28h and Qudos 28hP as “Flow thermistor open circuit or disconnected”. Match…E37Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE37 – Return thermistor open circuit or disconnectedKeston documents E37 for the Qudos 28h and Qudos 28hP as “Return thermistor open circuit or disconnected”. Match…E38Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE38 – DHW thermistor open circuit or disconnectedKeston documents E38 for the Qudos 28h and Qudos 28hP as “DHW thermistor open circuit or disconnected”. Match…E40Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE40 – Flue thermistor open circuit or disconnectedKeston documents E40 for the Qudos 28h and Qudos 28hP as “Flue thermistor open circuit or disconnected”. Match…E52Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE52 – Flue overheatKeston documents E52 for the Qudos 28h and Qudos 28hP as “Flue overheat”. Match the code to this…E67Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE67 – Water pressure below 0.2 barKeston documents E67 for the Qudos 28h and Qudos 28hP as “Water pressure below 0.2 bar”. Match the…E70Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE70 – Cabinet overheatKeston documents E70 for the Qudos 28h and Qudos 28hP as “Cabinet overheat”. Match the code to this…E73Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE73 – Code plug errorKeston documents E73 for the Qudos 28h and Qudos 28hP as “Code plug error”. Match the code to…E74Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE74 – Supply voltage below 190 VKeston documents E74 for the Qudos 28h and Qudos 28hP as “Supply voltage below 190 V”. Match the…E75Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE75 – Supply voltage above 270 VKeston documents E75 for the Qudos 28h and Qudos 28hP as “Supply voltage above 270 V”. Match the…E76Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE76 – Solar panel sensor short circuitKeston documents E76 for the Qudos 28h and Qudos 28hP as “Solar panel sensor short circuit”. Match the…E77Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE77 – Solar panel sensor open circuitKeston documents E77 for the Qudos 28h and Qudos 28hP as “Solar panel sensor open circuit”. Match the…E95Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE95 – Solar tank sensor short circuitKeston documents E95 for the Qudos 28h and Qudos 28hP as “Solar tank sensor short circuit”. Match the…E96Keston · Keston Qudos 28h and Qudos 28hP heat-only boilers · United KingdomE96 – Solar tank sensor open circuitKeston documents E96 for the Qudos 28h and Qudos 28hP as “Solar tank sensor open circuit”. Match the…C0Keston · Keston System S30 system boiler · United Kingdom and IrelandC0 – Keston System S30 error codeKeston documents C0 for the original System S30 system boiler as “BCC activation fault”. Boiler-chip-card activation or configuration…C2Keston · Keston System S30 system boiler · United Kingdom and IrelandC2 – Keston System S30 error codeKeston documents C2 for the original System S30 system boiler as “BCC fault”. Boiler-chip-card fault. This is the…F0Keston · Keston System S30 system boiler · United Kingdom and IrelandF0 – Keston System S30 error codeKeston documents F0 for the original System S30 system boiler as “Unconfigured PCB”. The boiler control board is…F1Keston · Keston System S30 system boiler · United Kingdom and IrelandF1 – Keston System S30 error codeKeston documents F1 for the original System S30 system boiler as “Low water pressure”. The sealed heating-system pressure…F2Keston · Keston System S30 system boiler · United Kingdom and IrelandF2 – Keston System S30 error codeKeston documents F2 for the original System S30 system boiler as “Flame loss”. The burner flame was lost…F3Keston · Keston System S30 system boiler · United Kingdom and IrelandF3 – Keston System S30 error codeKeston documents F3 for the original System S30 system boiler as “Fan fault”. The combustion fan or its…F4Keston · Keston System S30 system boiler · United Kingdom and IrelandF4 – Keston System S30 error codeKeston documents F4 for the original System S30 system boiler as “Flow thermistor fault”. The boiler has detected…F5Keston · Keston System S30 system boiler · United Kingdom and IrelandF5 – Keston System S30 error codeKeston documents F5 for the original System S30 system boiler as “Return thermistor fault”. The boiler has detected…F6Keston · Keston System S30 system boiler · United Kingdom and IrelandF6 – Keston System S30 error codeKeston documents F6 for the original System S30 system boiler as “Outside sensor failure”. The optional outside-temperature sensor…F7Keston · Keston System S30 system boiler · United Kingdom and IrelandF7 – Keston System S30 error codeKeston documents F7 for the original System S30 system boiler as “Low mains voltage”. The incoming mains voltage…F9Keston · Keston System S30 system boiler · United Kingdom and IrelandF9 – Keston System S30 error codeKeston documents F9 for the original System S30 system boiler as “Unconfigured PCB”. The boiler control board is…FAKeston · Keston System S30 system boiler · United Kingdom and IrelandFA – Keston System S30 error codeKeston documents FA for the original System S30 system boiler as “Flow/return reversed”. The boiler has detected reversed…FUKeston · Keston System S30 system boiler · United Kingdom and IrelandFU – Keston System S30 error codeKeston documents FU for the original System S30 system boiler as “Flow/return differential above 50°C”. The temperature difference…L1Keston · Keston System S30 system boiler · United Kingdom and IrelandL1 – Keston System S30 error codeKeston documents L1 for the original System S30 system boiler as “Flow temperature overheat or no water flow”.…L2Keston · Keston System S30 system boiler · United Kingdom and IrelandL2 – Keston System S30 error codeKeston documents L2 for the original System S30 system boiler as “Ignition lockout”. The boiler failed to establish…L4Keston · Keston System S30 system boiler · United Kingdom and IrelandL4 – Keston System S30 error codeKeston documents L4 for the original System S30 system boiler as “Flow thermistor fault”. The boiler has detected…L5Keston · Keston System S30 system boiler · United Kingdom and IrelandL5 – Keston System S30 error codeKeston documents L5 for the original System S30 system boiler as “Return thermistor fault”. The boiler has detected…L6Keston · Keston System S30 system boiler · United Kingdom and IrelandL6 – Keston System S30 error codeKeston documents L6 for the original System S30 system boiler as “False flame lockout”. A flame signal was…L9Keston · Keston System S30 system boiler · United Kingdom and IrelandL9 – Keston System S30 error codeKeston documents L9 for the original System S30 system boiler as “Unconfigured PCB”. The boiler control board is…LCKeston · Keston System S30 system boiler · United Kingdom and IrelandLC – Keston System S30 error codeKeston documents LC for the original System S30 system boiler as “Five boiler restarts in 15 minutes”. The…BLOCKED FLUE CONDENSATEKeston · Keston System² S30 gas boiler · United Kingdom and IrelandBLOCKED FLUE CONDENSATE – Keston System² S30 error codeKeston documents “Blocked flue or condensate” for the System² S30. This display message identifies a boiler-detected fault or…FAN FAULTKeston · Keston System² S30 gas boiler · United Kingdom and IrelandFAN FAULT – Keston System² S30 error codeKeston documents “Fan fault” for the System² S30. This display message identifies a boiler-detected fault or safety condition;…FLAME LOSSKeston · Keston System² S30 gas boiler · United Kingdom and IrelandFLAME LOSS – Keston System² S30 error codeKeston documents “Flame loss” for the System² S30. This display message identifies a boiler-detected fault or safety condition;…FLAME ON BEFORE GAS ONKeston · Keston System² S30 gas boiler · United Kingdom and IrelandFLAME ON BEFORE GAS ON – Keston System² S30 error codeKeston documents “Flame detected before gas command” for the System² S30. This display message identifies a boiler-detected fault…FLOW THERMISTOR FAULTKeston · Keston System² S30 gas boiler · United Kingdom and IrelandFLOW THERMISTOR FAULT – Keston System² S30 error codeKeston documents “Flow thermistor fault” for the System² S30. This display message identifies a boiler-detected fault or safety…GAS VALVE FAULTKeston · Keston System² S30 gas boiler · United Kingdom and IrelandGAS VALVE FAULT – Keston System² S30 error codeKeston documents “Gas valve fault” for the System² S30. This display message identifies a boiler-detected fault or safety…IGNITION LOCKOUTKeston · Keston System² S30 gas boiler · United Kingdom and IrelandIGNITION LOCKOUT – Keston System² S30 error codeKeston documents “Ignition lockout” for the System² S30. This display message identifies a boiler-detected fault or safety condition;…LOW MAINS VOLTAGEKeston · Keston System² S30 gas boiler · United Kingdom and IrelandLOW MAINS VOLTAGE – Keston System² S30 error codeKeston documents “Low mains voltage” for the System² S30. This display message identifies a boiler-detected fault or safety…