Error E193

Safety precautions:

1) If you smell gas, stop immediately: turn off gas at the meter, open windows, do not operate electrical switches or boiler controls, and call your gas emergency number and a Gas Safe engineer.

2) Isolate mains electrical supply to the boiler before removing any covers or touching internal components. Do not attempt gas or sealed-flue work unless you are Gas Safe qualified.

3) Wear gloves and eye protection for working on radiators and valves. Be careful with hot water and steam when bleeding radiators.

4) Do not repeatedly reset the boiler more than once or twice — persistent lockouts require a professional.

Initial homeowner checks (safe, do these first):

1) Note the conditions when E193 appeared (after a power cut, after filling, after radiators bled, etc.).

2) Check boiler water pressure on the gauge. Aim for around 1.0–1.5 bar (follow your manual). If pressure is below 0.5–0.8 bar top up via the filling loop to about 1.2 bar, following the boiler manual. After topping up, try a reset.

3) Attempt a simple reset: press and hold the reset/select button (or turn selector to R) for 5–10 seconds. Watch whether the code clears and whether the boiler attempts ignition.

4) Make sure room thermostat and timer are calling for heat and that the boiler is set to heating mode.

5) Check that all radiator thermostatic valves and isolation valves on the boiler flow and return are open.

6) Listen and feel: when the boiler requests heat, place your hand on the pump body (externally) and pipes to see if you feel a vibration or warmth. Also listen for the pump running (a faint whirr). If the pump is silent and you have CH demand the pump may not be running.

Diagnostic and simple fix steps (homeowner-level):

1) Bleed radiators to remove trapped air. Start with the highest radiators in the property and work downwards. Re-check and re-pressurise to ~1.2 bar if pressure falls.

2) Check the pump isolation valves (usually on either side of the pump). If they are closed, open them (quarter-turn valves). If they are stuck, do not force excessively; call an engineer.

3) Check for obvious obstructions at the external flue terminal (birds, leaves) only around the terminal area — do not dismantle the flue. Blocked flue recirculation can sometimes affect operation.

4) Verify that the flow and return temperature sensors are clipped correctly to their respective pipes (they must be clipped on firmly to the correct pipe, not hanging in the air). Re-clip if obvious misplacement is seen and safe to do so.

5) If the pump appears stuck but you are confident and competent: isolate mains power to the boiler, remove the front cover (if comfortable and following manual), and visually inspect the pump for seized impeller or debris. Do not attempt to disassemble the pump unless qualified; instead note observations for the engineer.

6) If the system has poor circulation after bleeding and valves are open, the system may be heavily sludged. This often needs a professional (powerflush or inhibitor treatment) to restore flow.

7) If you have the skills and will only after isolating power: you may check pump wiring for loose connectors and ensure the pump is receiving supply when the boiler calls for heat (use a multimeter to check for correct voltage). Do not measure live voltages unless competent; if unsure, stop and call a professional.

When to call a professional (and what they will check):

1) Call a Gas Safe registered engineer if E193 persists after the above steps, or if the pump does not run when the boiler calls for heat, if you suspect internal wiring faults, a seized pump, blocked heat exchanger, or if you are not confident performing the safe checks.

2) The engineer will check pump electrical supply and operation, replace or free a seized pump, inspect and clear restrictions in the primary heat exchanger and pipework, check and replace faulty sensors, confirm correct venting and flue operation, test PCB communications, and perform a system clean (powerflush) or repairs as needed.

3) Do not attempt gas valve, PCB replacement, or heat exchanger work yourself. These require a Gas Safe engineer and specialist testing equipment (combustion analyzer, µA flame sensing checks, etc.).

Final notes:

- E193 is often a protect-mode fault to prevent damage; it can clear after purging air, restoring pressure and confirming pump operation, but persistent faults need a qualified engineer. - If at any point you smell gas, or see water leaks from the boiler, or are unsure about any step, isolate the appliance and call a Gas Safe engineer immediately.