Error E163

Safety first

- If you smell gas, leave the property immediately, call emergency services or the gas emergency number and do not interact with the boiler.

- Always isolate electricity to the boiler at the fused spur before removing the casing. If you are unsure how to do this, do not attempt to open the boiler.

- Do not attempt to work on gas valves, burner, or sealed hydraulic parts unless you are a Gas Safe engineer. Simple checks below are limited to external observations, power cycling and basic electrical checks if you are comfortable and competent.

Initial homeowner checks (safe, no tools beyond basic)

1) Note the exact error code and sequence (E163 and whether it says s.c. or o.c.). Record boiler model and serial for the engineer if needed. 2) Try a powered reset: follow the boiler manual reset procedure (usually a reset button or switch) or turn electrical supply off for 30 seconds and back on. If the error clears and does not return, monitor for reoccurrence. 3) Check system water pressure on the gauge; if pressure is very low (<1.0 bar) top-up to the recommended pressure (usually ~1.2–1.5 bar) following the manual. Some faults only appear when pressure is abnormal. 4) Check whether central heating still works and whether any hot water is produced. This helps determine if the fault is DHW-specific.

Visual/wiring checks (if comfortable, otherwise skip and call an engineer)

5) With the mains isolated at the boiler, remove the outer case only if you are confident and if the boiler is designed to be user-accessible. Inspect the sensor wiring and connectors that run to the DHW NTC — look for loose plugs, corrosion, chafing, water ingress or obvious damage. Re-seat any plug-in connectors firmly. 6) If connectors were loose or wet, dry and re-fit, restore power and test. If the error was a transient connection, this may clear it.

Electrical diagnostic checks (only if you have a multimeter and electrical competence)

7) With power isolated, identify the DHW NTC sensor terminals (refer to service manual or wiring diagram if available). Measure continuity between sensor wires and the PCB connector to rule out a broken wire. An open between sensor and PCB suggests wiring/faulty connector. 8) Measure the sensor resistance directly at the sensor leads: an NTC will show a finite resistance and should change when warmed or cooled (resistance falls as temperature rises). If the meter reads infinite (open circuit) or very low/near zero (short circuit), the sensor is faulty. If resistance at the PCB connector differs from resistance at the sensor, the wiring is the issue. 9) You can verify temperature response by gently warming the sensor (for example with warm water, not a hot flame) and checking that resistance changes. If resistance does not change, replace sensor.

If you find a clear wiring fault or the sensor is open/shorted

10) If you are competent and local regulations permit, a user-replaceable NTC probe can be replaced following the manufacturer’s instructions. Otherwise, stop and call a Gas Safe engineer. 11) After replacing or repairing the sensor/wiring, reassemble the boiler, restore power and test. Reset any errors and test hot water demand to confirm normal operation.

When to call a professional (required in most cases)

- If you are not comfortable isolating mains, opening the boiler case or using a multimeter. - If the fault persists after re-seating connectors and basic resets. - If internal wiring needs replacement, or the sensor is integrated into a heat exchanger or in a location requiring boiler dismantling. - If the fault returns intermittently or other errors are present (overtemperature, repeated lockouts).

What to tell the engineer

- Provide model and serial, the exact error code (E163 s.c. or o.c.), what you observed (no hot water, CH OK or not), what checks you carried out and any connector findings. This saves time on the visit and helps the engineer bring the correct replacement parts.

Final notes

- Do not guess or improvise on sensor wiring or replace parts without a qualified engineer if the component is internal or requires system draining. - Repeated sensor faults can indicate moisture ingress, corrosion, or PCB connector issues; a professional inspection will determine root cause and safe repair.