Error E164

Safety precautions:

1. If you smell gas or suspect a gas leak, leave the property immediately, call the gas emergency number and do not operate electrical switches. 2. Isolate electrical power to the boiler before accessing internal parts for inspection. 3. Do not attempt to repair gas valves, burners, or sealed components unless you are a Gas Safe registered engineer. 4. Frequent resetting of the boiler is not recommended and may hide a persistent fault or cause further damage.

Initial homeowner checks (safe DIY):

1. Record the exact code sequence shown on the display (sometimes E1xx then further digits appear). Note if any other codes appear alongside E164. 2. Check the boiler pressure gauge on the front panel. Target pressure for most Baxi systems is about 1.0–1.5 bar when cold. If pressure is below about 0.8 bar, top up the system using the filling loop following the manufacturer instructions, then attempt a reset. 3. Try a single reset: press and hold the boiler reset button as per your manual (usually 5–10 seconds). Do not repeatedly reset. 4. Check visible pipework and radiators for leaks; a loss of pressure may indicate a leak. 5. Ensure external flue terminal and air intake are not blocked by debris, bird nests or snow/ice. 6. Listen for the pump when demand is present — if you hear no pump operation and radiators remain cold, there may be a circulation issue contributing to sensor readings.

Diagnostic steps (for a competent DIYer with basic tools) and what an engineer will do:

1. After a reset and if E164 persists, note whether the fault occurs immediately or after the boiler attempts to run—this timing helps narrow down whether the sensor is reporting a static fault or an out-of-range condition during operation. 2. If system pressure was low and topping up cleared the code, monitor pressure over a few days. If pressure falls again, find and repair the leak or call an engineer. 3. Check the visible wiring to the boiler for obviously loose or damaged connectors behind a removable panel (do not open gas or burner compartments). A loose connector to a pressure transducer or sensor can cause a false fault. 4. If you are competent and it is safe/legal where you are, an engineer or trained technician can measure the sensor outputs: thermistors are checked with an ohmmeter against the manufacturer NTC chart (typically must read within ±10% of the stated ohms for the temperature). Pressure transducers may produce a voltage or mA signal; they should be tested per Baxi service instructions. 5. If sensor readings are out of specification, replace the faulty sensor (return NTC, flow NTC or pressure transducer as identified). If wiring and sensor read correctly, the fault may be on the PCB input stage and the PCB may need replacement. 6. Check pump operation and remove airlocks by bleeding radiators and purging the system if circulation problems were present; trapped air or a seized pump can cause abnormal sensor readings and lockouts. 7. After any repair or part replacement, the boiler will typically need a reset and possibly calibration following the manufacturer's procedure.

When to call a professional:

1. If the basic checks (pressure, reset, visible wiring, clear flue) do not clear E164, stop and call a Gas Safe registered engineer. 2. Any tests or replacements of sensors, pressure transducers, the pump, gas components, or the PCB must be performed by a qualified engineer. 3. If you are unsure at any stage, or you find evidence of gas smell, water leaks, or internal damage, arrange an urgent professional visit.

Notes and final guidance:

1. E164 is not normally a simple cosmetic fault; it indicates a protective lockout tied to safety monitoring. 2. Avoid repeatedly resetting the boiler; persistent faults need a proper diagnostic. 3. Keep a written record of the error code, actions taken, and dates for the engineer. 4. No repair cost estimates are provided here; your Gas Safe engineer will give a quote once the fault is diagnosed.