BoilerFaultCodesAriston 1 03 Fault Code
Also written as 103 — same fault.
The Ariston 1 03 fault code means: your boiler is struggling to move water through the system, usually because there is trapped air, a closed valve, or a blockage preventing proper flow.. It appears on 14 Ariston models in our database.
Technical description: Insuffi cient circulation
DIY fix possible
Check all radiator valves in your home are fully openCheck your boiler's pressure gauge and top up the system to between 1.0 and 1.5 bar if lowBleed any radiators that feel cold at the top to release trapped air
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Ariston models that show the 1 03 fault code
Click a model for the full fault code list and model-specific repair notes.
- Challenger 80E Repair: £120-250
- Clas HE 24 Repair: £120-250
- Clas HE 28 Repair: £120-250
- Clas HE 35 Repair: £120-250
- Clas HE Evo Repair: £120-250
- Clas Net One Repair: £100-£250
- Clas One Repair: £100-200
- Clas System 28 Repair: £120-£250
- E-Combi Evo Repair: £120-£250
- E-Combi One Repair: £120-250
- E-Combi One 24 Repair: £100-£350
- E-Combi One 30 Repair: £120-250
- Egis Repair: £120-250
- Microsystem 15 Repair: £120-250
Source
Ariston 1 03 fault code information on this page is sourced and cross-checked against the official Ariston service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026