BoilerFaultCodesJohnson Starley E03 Fault Code
The Johnson Starley E03 fault code means: your boiler has detected a problem with how it is venting exhaust gases or an issue with internal air pressure, causing it to shut down for safety.. It appears on 12 Johnson Starley models in our database.
Technical description: Flue gas thermostat intervention / Pressure switch
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 →Johnson Starley models that show the E03 fault code
Click a model for the full fault code list and model-specific repair notes.
- C10d Repair: £100-220
- C16d Repair: £120-250
- C16u Repair: £100-250
- C26d Repair: £120-£250
- Comet 100 Repair: £120-350
- Comet 60 Repair: £90-250
- Comet 80 Repair: £90-280
- J32 System ET Repair: £120-280
- Optima E20 Repair: £120-350
- Warmaflow F80E Repair: £90-250
- Warmaheat Repair: £120-350
- Warmcair DW Repair: £120-280
Source
Johnson Starley E03 fault code information on this page is sourced and cross-checked against the official Johnson Starley service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026