Error S.46

Safety precautions:

1. Do not tamper with gas valves, ignition components, electrodes, wiring or internal boiler parts. Working on gas appliances is dangerous and must be done by a Gas Safe registered engineer.

2. If you smell gas, leave the property immediately and call the gas emergency number. Do not operate electrical switches or the boiler.

3. If freezing is possible and you need to isolate the boiler, use the site main switch or consult your installer. Do not operate the boiler if you are unsure about safety.

Initial checks a homeowner can do:

1. Note exactly when S.46 appears (during heating, hot water, intermittent, always at low demand). This information helps the engineer.

2. Check other gas appliances in the property to see if they are working. If everything else has no gas, contact your gas supplier.

3. Check boiler pressure on the gauge. If pressure is very low (below about 1 bar) top up following the boiler manual. Low pressure can affect operation but is not the most common cause of S.46.

4. Check the flue terminal and air inlet (outside the property) for obvious blockages (bird nest, leaves, debris). Do not insert objects into the flue. Clear only light debris from outside if safe to do so.

5. Inspect the visible condensate discharge pipe (usually plastic) for blockages or frozen condensate in cold weather. If the condensate pipe is frozen, thaw it with warm (not boiling) water or seek an engineer.

6. Try a single reset: press the boiler fault/clear or reset button as the manual indicates (press and hold for about one second to clear a fault). If the code clears and the boiler runs normally, monitor for recurrence. Do not repeatedly reset more than three times if the fault persists.

If the fault persists or recurs:

1. Do not attempt internal repairs. Record the fault code, the conditions when it happened, and any related behaviour (noisy ignition, long ignition, repeated lockouts).

2. Call a Gas Safe registered engineer and give them the S.46 code and your observations. Tell them whether you cleared the fault and how many reset attempts were made.

What a Gas Safe engineer will typically check and do (for information only):

1. Check gas supply and gas pressure at the appliance and confirm correct gas type/settings. Look for intermittent supply issues.

2. Inspect ignition electrode and ignition lead for corrosion, wear, or incorrect gap; clean or replace if needed.

3. Check flame detection circuitry and wiring to the PCB and any flame sensor or ionisation detection components.

4. Inspect the burner and combustion chamber for sooting, condensate or blockages; clean burner, check condensate drainage and combustion chamber condition.

5. Check the flue and air intake integrity and for wind/pressure effects causing flame instability.

6. Test and, if necessary, replace components such as the gas valve, mass flow sensor, ignition electrode, or PCB if they are failing to regulate and detect flame at minimum load.

7. Run live diagnostics and monitor operation at low and higher loads to ensure the problem is resolved.

Final note: S.46 is a safety-related flame loss message. If a simple reset and the basic checks above do not permanently clear the code, arrange for a qualified Gas Safe engineer to investigate and repair. Do not try to bypass safety interlocks or operate the boiler if you suspect combustion or gas faults.