Error S.06

Safety precautions:

1) If you smell gas or a carbon monoxide alarm is sounding, leave the building immediately and call your local gas emergency number and/or emergency services. Do not attempt to investigate the boiler.

2) Do not open the sealed boiler casing, touch the gas supply, or attempt electrical repairs. Any internal checks or repairs must be done by a Gas Safe registered engineer.

3) Isolate electrical power to the boiler at the external switch or fused spur before allowing any engineer to work on internal components.

4) Keep the area around flue terminals clear and ensure good ventilation when checking external components.

Initial checks a homeowner can safely do:

1) Note the exact display behavior and when S.06 appears (e.g., immediately on heat demand, after burner shuts down, intermittently). This information is useful for the engineer.

2) Attempt a simple reset: turn the boiler off at the front or main switch, wait 30–60 seconds, then turn back on. If S.06 clears and does not return, monitor the boiler through a couple of heating cycles. If it returns, proceed to the next checks.

3) Check external flue terminal and air intake for obvious blockages (bird nests, leaves, snow, debris). Remove minor external obstructions safely from the outside only—do not insert objects into the flue.

4) Check that external controls/thermostats are set correctly (heating demand is present) and that any timer or room thermostat is not causing rapid on/off cycles.

5) Listen during a heating cycle: can you hear the fan running when the boiler is idle or long after the burner has stopped? Make a note of this behavior.

Further diagnostic steps for recording before calling an engineer (do not open the boiler):

1) If the fault appears after a restart, record whether the fan continues to run for an unusually long time after the burner stops, and whether other errors appear in the display.

2) Check boiler water pressure on the gauge; note the value. While not a direct cause of fan overrun, abnormal pressures or other simultaneous faults can help diagnosis.

3) If comfortable, take a clear photo of the flue terminal and the boiler display/error code to send to the engineer.

What a professional engineer will check and possible fixes they will carry out:

1) Visual and electrical connection checks: inspect fan motor connections and plugs to the PCB for corrosion, looseness or disconnection and reseat connectors as required.

2) Fan motor and hall sensor testing: measure supply to the fan, check for correct hall sensor signals and motor resistance; replace the fan assembly or hall sensor if faulty.

3) Wiring harness and PCB checks: test wiring continuity between fan and PCB and check for damage to the harness; if the PCB shows fault behavior they will test outputs and inputs and replace the PCB if defective.

4) Mechanical checks: inspect the fan for mechanical stiffness, foreign objects, or seized bearings; clean or replace the fan assembly if needed.

5) Flue and airflow checks: verify flue temperatures and that the flue is not blocked internally; clean or repair flue components and check the flue gas temperature limiter if suspected.

6) System test: after any repair or replacement, the engineer will run the boiler through several heating cycles to confirm correct fan cut-off timing and that S.06 does not reoccur.

Final notes and when to call a professional:

1) If S.06 persists after the simple homeowner checks (reset, clear external blockage, confirm controls), contact a Gas Safe registered engineer. The fault involves fan control and electrical systems that must be safely diagnosed and repaired by a qualified technician.

2) Do not attempt to dismantle or replace the fan, PCB, wiring, or any gas-carrying parts yourself. Improper work can create safety risks.

3) If you experience any additional symptoms such as persistent loss of heat, unusual noises, the smell of gas, or CO alarm activation, stop using the boiler and seek emergency help immediately.