BoilerFaultCodesGlow-worm F13 Fault Code
The Glow-worm F13 fault code means: your boiler's main internal computer has developed a memory or communication error and can no longer control the heating system safely.. It appears on 12 Glow-worm models in our database.
Technical description: Main PCB fault
What causes the Glow-worm F13 fault?
This fault occurring means the boiler’s internal computer has suffered a serious electronic failure and can no longer process data correctly. It is often caused by a physical component failure on the circuit board or loose wiring connections that disrupt the flow of information. Factors like age, heat stress over many years, or power surges are the most likely reasons the board has stopped working.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Glow-worm models that show the F13 fault code
Click a model for the full fault code list and model-specific repair notes.
- 30ci Plus Repair: £280-450
- Ci Plus Repair: £250-£450
- Flexicom 18sx Repair: £90-180
- Flexicom hx Repair: £90-180
- Flexicom sx Repair: £90-180
- Ultracom 2 CXI Repair: £90-160
- Ultracom 2 HXI Repair: £90-160
- Ultracom 24cx 30cx Repair: £90-160
- Ultracom 35 Store Repair: £90-160
- Ultracom cxi Repair: £90-160
- Ultracom hxi Repair: £90-160
- Xtramax HE Repair: £250-£450
Source
Glow-worm F13 fault code information on this page is sourced and cross-checked against the official Glow-worm service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026