HTP Error F05: Supply Over-Temperature Lockout
The boiler supply temperature is excessive (supply sensor exceeded about 230 F). With the red FAULT light and LOCKOUT flashing, this is a serious overheat safety lockout. We diagnose and repair it across Greater Vancouver — same-day and after-hours.
The boiler supply temperature is excessive (supply sensor exceeded about 230 F). With the red FAULT light and LOCKOUT flashing, this is a serious overheat safety lockout.
HTP fault codes can vary by model and series. Use this as a guide — the same code can have more than one cause. Our Technical Safety BC–licensed technicians read the code, confirm it against your unit's manual, and diagnose the true cause before any repair.
Likely causes of HTP error F05
- Insufficient water flow (stuck pump, air-bound system)
- Closed zone or isolation valves
- Clogged system filter/strainer
- Faulty supply temperature sensor
- Scaled or fouled heat exchanger
What you can safely check
- Check the pressure gauge is in the normal operating range
- Confirm not all heating zones are shut off and the pump is audible
Beyond these checks, do not open the unit or touch gas/electrical parts — BC law requires a licensed gas fitter. Call us for a proper diagnosis.
Error F05 usually leaves you without heat or hot water and can indicate a safety-related fault. Don't keep resetting it — call for priority after-hours HTP repair.
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Parts often behind HTP error F05
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HTP Error F05 Repair Across Metro Vancouver
Related HTP Safety & Overheat Codes
Frequently Asked Questions
Fix HTP Error F05 Today
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