Error E0

Safety precautions:

1. If you smell gas, leave the property immediately and call your gas emergency number — do not attempt any checks. 2. Turn the boiler off at the control panel and isolate electrical power at the mains before touching any wiring or internal components. 3. If you are unsure about any step, stop and call a Gas Safe engineer. Do not attempt to replace sensors or access gas-carrying parts unless you are qualified.

Initial checks a homeowner can do:

1. Check the boiler display and note whether E0 is constant or intermittent and whether any other fault lights are shown. 2. Check system water pressure on the pressure gauge (aim for about 1.0–1.5 bar when cold; Baxi guidance says 1–3 bar but most domestic systems are 1–1.5). If pressure is low, top up using the filling loop following the boiler manual. 3. Bleed radiators to remove air — trapped air can cause poor circulation and abnormal sensor readings. 4. Check for obvious leaks around the boiler and pipework that could cause low pressure or sensor immersion in water. 5. Check external flues and vents are not blocked (obstructed vents can cause other faults that affect operation).

Basic reset procedure to try (may clear temporary faults):

1. Locate the boiler reset button or selector (refer to the manual). 2. Press and hold the reset button for about 5–10 seconds, or set the selector to R and hold as specified in the manual. 3. Wait for the boiler to attempt to restart. 4. Do not keep resetting repeatedly if the fault returns — repeated resets can cause further damage and indicate a persistent problem.

If the fault persists after initial checks and a reset:

1. Record when the fault occurs (on demand for hot water, on CH call, after a cold start, after topping up pressure) and any other symptoms (no hot water, radiators cold, unusual noises). This information helps the engineer.

2. Do not open the boiler casing or touch internal wiring unless you are qualified. Loose or corroded sensor connections inside the boiler can sometimes be re-seated, but accessing them requires isolating power and understanding of boiler internals.

3. A qualified engineer will typically: a) confirm sensor fault by measuring sensor resistance/temperature with a multimeter (NTC sensors have a specific resistance curve), b) check wiring and connectors for continuity, corrosion or heat damage, c) check the PCB for related error records and communication faults, d) replace the faulty sensor(s) and test the system, and e) verify system pressure and circulation after repair.

When to call a professional:

1. Call a Gas Safe registered engineer if the E0 fault does not clear after the basic checks and a reset, if the code returns repeatedly, or if there are other error codes or persistent loss of heating/hot water. 2. Call immediately and leave the premises if you smell gas. 3. Sensor replacement, PCB faults, and internal electrical diagnostics must be handled by a qualified engineer for safety and warranty reasons.

Notes and best practice:

1. Keep a record of fault occurrences and any steps you have taken before the engineer arrives. 2. If topping up pressure, stop when the gauge reaches the recommended range to avoid over-pressurising. 3. Do not attempt to jury-rig or bypass sensors — these protect the boiler and your home. 4. Repeated E0 faults usually require professional diagnosis and potentially replacement of sensors or further electronic fault finding.