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Keston · Boilers and HVAC

Keston Celsius 25 and 25P condensing boilers

Product information, applicable models, official documentation and 15 indexed error-code explanations for Keston Celsius 25 and 25P condensing boilers.

Keston Celsius 25 and 25P condensing boilers
15indexed codes
1named models or series
1official links
Product overview

About Keston Celsius 25 and 25P condensing boilers

Keston Celsius 25 and 25P condensing boilers is indexed in the Boilers and HVAC directory for United Kingdom and Ireland. This page brings the available product context, model references, documentation and diagnostic codes together in one place.

The codes below apply only where the linked code page lists this product or model. Confirm the complete model identifier because manufacturers may reuse the same characters across different ranges, generations and control systems.

An error code describes a condition detected by the product; it does not prove that a named component has failed. Follow the exact manual, avoid repeated resets and use an appropriately qualified technician whenever checks require internal access.

Applicability

Models and series

Celsius 25; Celsius 25P; KC25; KC25P
Complete directory

All Keston Celsius 25 and 25P condensing boilers error codes

Showing 1–15 of 15

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…