Error CONNECTION

Safety first: if you smell gas, leave the property immediately and call the gas emergency service. Always isolate electrical power to the boiler at the fused spur or isolator switch before touching or opening covers. Do not attempt to repair or replace gas or live electrical components unless you are a qualified, Gas Safe registered engineer.

Initial simple checks a homeowner can safely do:

1) Record the exact error message and any other displayed codes or behaviour (e.g. won’t light, weird pressure readings). Take a clear photo of the display and boiler rating plate (model and serial number). This helps the engineer.

2) Power-cycle the boiler: switch off at the fused spur or isolator, leave it off for at least 5 minutes and then switch back on. Many transient communication faults clear with a full power-down. If it clears but returns intermittently, that points to an intermittent connection or failing electronics.

3) Check the boiler case and display are sitting correctly: ensure any door or control panel is fully closed and clipped home. Some models have a microswitch or interlock that will show faults if panels are not seated.

4) Look for obvious signs without opening the appliance: any visible water leaks, corrosion around the case, burn/heat marks, or rodent damage to external cables or the display wiring. If you find water or damage, turn off the boiler power and call a professional.

Further diagnostic steps (only non-live visual checks for a competent homeowner):

1) If the display is a separate detachable module and can be removed without exposing live parts, you may gently check that its connector is seated and that the cable is not visibly damaged. Only do this if the boiler is fully isolated from mains power and you are confident you can remove/replace covers without disturbing gas components. If unsure, stop and call an engineer.

2) Note any related symptoms such as frequent restarts, fluctuating pressure, or other fault codes appearing alongside CON. Those clues help the engineer narrow down whether the main PCB power supply or sensors are affected.

Why a professional should be called and what they will do:

- This fault commonly requires a technician because it involves live electronics and possibly gas safety checks. A Gas Safe registered engineer will safely isolate and open the boiler, inspect connector pins and wiring, test supply voltages and signals to the display and main PCB, and use diagnostic tools to identify whether the display PCB, main PCB, or wiring is at fault. On older EcoTEC Plus boards a common failure mode is aging electrolytic capacitors; a competent engineer may replace faulty components or the whole PCB as appropriate. Repairs to PCBs or replacements must be performed by qualified personnel to meet safety and regulatory requirements.

What to prepare for the engineer and next steps:

- Provide model and serial number, last service date, the CON error and any other codes, photos, and the results of your reset attempt. If the fault is intermittent, describe when it occurs (startup, after run time, after power loss). The engineer may need to leave the boiler off until repaired if the fault prevents safe operation.

Important reminders:

- Do not attempt live electrical measurements or PCB soldering yourself. Opening and working on the boiler's internal components without qualification is dangerous and illegal for gas appliances in many jurisdictions. No repair cost estimates are provided here; the engineer will advise on options (repair PCB, replace display, or replace PCB) after diagnosis.