BoilerFaultCodesJohnson Starley 31 Fault Code
The Johnson Starley 31 fault code means: your boiler has lost connection with its internal air temperature sensor, which means it cannot safely monitor the heat level and has stopped working.. It appears on 5 Johnson Starley models in our database.
Technical description: Duct air temperature sensor open circuit. Temperature sensor not connected or failed. Check wiring connections. Check sensor continuity.
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 →Avoid the next call-out bill
A cover plan would handle faults like 31: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
Johnson Starley models that show the 31 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Johnson Starley 31 fault code information on this page is sourced and cross-checked against the official Johnson Starley service / installation manuals for each affected model.
- Johnson Starley C10d manual (PDF)
- Johnson Starley C16d manual (PDF)
- Johnson Starley C16u manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026