Error E.02 – .48

Safety precautions:

1) If you smell gas or see/hear anything that suggests a gas leak (rotten egg smell, hissing, dead plants near the appliance) evacuate the property immediately and call your gas emergency number. Do not try to diagnose electrical/gas faults yourself in that case.

2) If you are not competent with electrical wiring or opening the boiler casing, do not open the boiler or attempt internal repairs. Work on the internal electronics or gas parts must be done by a Gas Safe registered or suitably qualified engineer.

3) Turn off mains electricity to the boiler at the isolator or consumer unit before you open the casing or touch any wiring. Only do this if you are competent and it is safe to do so.

Initial checks a homeowner can do (no tools required):

1) Note the exact error code and when it appeared (E.02 – .48). This helps an engineer diagnose later.

2) Check the external device: is it powered or are its batteries charged? If it’s a wireless thermostat, replace batteries or confirm mains power to its receiver.

3) Ensure the external device is switched on and within normal range of the boiler receiver or wireless module. Move the thermostat temporarily closer if possible.

4) If the external device is a smart hub or app-controlled thermostat, check the app for connection status; reboot the hub/router and the thermostat device if applicable.

5) If you’ve recently changed or added any controls (new thermostat, new smart device, new wiring), note that — this often triggers pairing/configuration faults.

Basic reset and simple fixes:

1) Try a normal boiler reset: find the reset button or follow the boiler control reset procedure (press and hold the reset for 5–10 seconds, or use the selector to R/reset as per your model). Wait for the boiler to attempt to restart and watch whether the E.02 – .48 returns.

2) After resetting the boiler, also restart/reboot the external device (power cycle it or replace batteries) and try to re-establish a connection from the external device side (put thermostat/hub into its pairing mode as the manufacturer instructs).

3) If the external device is wireless and has a separate receiver or RF module fitted to the boiler, ensure that receiver is powered and hasn’t come loose.

If the external device is wired to the boiler (thermostat wires):

1) Only proceed if you are competent. Turn off mains electricity to the boiler at the consumer unit and isolate the boiler. Confirm power is off.

2) Open the thermostat housing (or the boiler wiring compartment if accessible) and check that the thermostat wires are secure in the correct terminals. Typical connections are to COM/NO or terminals labelled for room stat, but consult the thermostat and boiler wiring diagrams first.

3) Look for signs of loose screws, damaged wire insulation, corrosion or disconnected wires. Re-secure properly and close the casing.

4) Restore power and test. If the E.02 – .48 persists, power down again and avoid further internal changes — call an engineer.

Re-pairing and configuration steps (general guidance):

1) Consult the manual for the external device (thermostat or hub) and the boiler wiring/communications section for the correct pairing procedure and compatibility notes.

2) Place the thermostat/hub into its pairing mode, then follow the boiler or receiver pairing steps. Some thermostats pair directly to a wireless receiver fitted to the boiler; others use an intermediary hub.

3) If pairing fails repeatedly, try removing the device from the hub/app and re-adding it, or perform a factory reset of the external device per its manual before re-pairing.

4) Keep devices close together while pairing and remove potential sources of RF interference (other wireless devices, metal cabinets) during the attempt.

When to call a professional (must do):

1) If the error returns after you’ve tried reset, battery/power checks and re-pairing, call a Gas Safe registered engineer or your installer. This error can indicate a failed PCB, CSU, wireless module or incorrect internal configuration which requires specialist tools and knowledge.

2) If you are not confident with electrical wiring or if the thermostat connections are inside the boiler casing, do not attempt internal diagnostics — call an engineer.

3) If the boiler shows other faults at the same time (no flame, low pressure, overheating) or repeatedly locks out, arrange professional service.

What to tell the engineer when you call:

1) Provide the exact error code (E.02 – .48), when it first occurred and how often it repeats.

2) Say what external device is connected (brand/model of thermostat, wireless receiver or hub) and whether it was working before or recently changed.

3) Tell them what you have already tried (reset, battery change, rebooting devices, moving thermostat closer).

Additional notes and cautions:

1) This fault is usually a communications/configuration problem rather than an immediate gas safety issue, but it can leave your heating or hot water inoperable. Treat repeated lockouts seriously and get a professional diagnosis.

2) Do not keep repeatedly resetting the boiler more than a couple of times — note occurrences and call an engineer if the fault returns.

3) If a new thermostat or smart control was recently installed, check compatibility with Baxi systems and consider reverting to the original control until an engineer can confirm correct setup.