Dunkirk Error b26: External limit / LWCO / pressure switch open - soft lockout
Soft (auto-reset) lockout: an external limit, low-water cutoff (LWCO), or the 3.5in pressure switch wired into the auto-reset circuit has opened. Burner is held off (about 2.5 minutes). Display flashes '9' then 'b' with code 26. We diagnose and repair it across Greater Vancouver — same-day and after-hours.
Soft (auto-reset) lockout: an external limit, low-water cutoff (LWCO), or the 3.5in pressure switch wired into the auto-reset circuit has opened. Burner is held off (about 2.5 minutes). Display flashes '9' then 'b' with code 26.
Dunkirk 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 Dunkirk error b26
- Low water / low system pressure tripping the LWCO
- External high-limit or safety switch opened
- Air in the system reducing flow
- Faulty LWCO probe or wiring
- Tripped 3.5in pressure switch
What you can safely check
- Check the system pressure gauge - if low, top up via the fill valve to about 12-15 psi cold (if you know how)
- Look for visible leaks around the boiler and piping
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.
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Parts often behind Dunkirk error b26
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Dunkirk Error b26 Repair Across Metro Vancouver
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