BoilerFaultCodesGlow-worm S.96 Fault Code
Also written as S96 — same fault.
The Glow-worm S.96 fault code means: your boiler is temporarily pausing to perform a routine check on its internal temperature sensors before it can provide heating or hot water.. It appears on 12 Glow-worm models in our database.
Technical description: Return-Sensor check is running, demand (DHW or heating) is blocked
What causes the Glow-worm S.96 fault?
This occurs when the boiler's control board detects a potential discrepancy between the flow and return temperature sensors and needs to verify their accuracy. It is often caused by a sensor that is starting to drift out of its calibrated range or a slight delay in the water temperature changing when the pump starts. While usually a brief self-test, persistent pauses suggest the internal sensors are no longer providing consistent readings to the computer.
DIY fix possible
Wait up to 15 minutes for the internal test to completeEnsure all radiator valves are open to help water flowCheck if the system pressure is between 1.0 and 1.5 bar
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 S.96 fault code
Click a model for the full fault code list and model-specific repair notes.
- Flexicom 18sx Repair: £100-£190
- Flexicom cx Repair: £100-220
- Flexicom hx Repair: £100-£190
- Flexicom sx Repair: £100-£190
- Ultracom 2 CXI Repair: £100-180
- Ultracom 2 HXI Repair: £100-180
- Ultracom 2 SXI Repair: £0-120
- Ultracom 24cx 30cx Repair: £100-180
- Ultracom 35 Store Repair: £100-180
- Ultracom cxi Repair: £100-180
- Ultracom hxi Repair: £100-180
- Ultracom sxi Repair: £0-120
Source
Glow-worm S.96 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