Error C6 216

Safety precautions:

1) If you smell gas or suspect a carbon monoxide leak, leave the building immediately and call the gas emergency number and/or your emergency services. Do not attempt repairs. 2) If you are not competent with electrical/gas appliances do not open the boiler casing. Working on internal components, the gas valve, flue or PCB must only be done by a Gas Safe registered engineer. 3) Before any basic checks, turn off the boiler at the main isolator and be cautious around hot or sharp parts.

Initial homeowner checks you can safely perform:

1) Note the exact error code and any sequence numbers or messages shown and the time it happened – useful for the engineer. 2) Try a single reset: follow your boiler manual (press reset button or hold the dial to reset point for 3 seconds). If the fault returns immediately or after a short run, do not keep resetting repeatedly. 3) Check the external flue terminal for visible blockages (nests, leaves, debris), and ensure outside air inlet vents are clear. 4) Check for frozen or blocked external condensate pipe (common in cold weather) and carefully thaw if frozen. 5) Confirm the boiler has power and the isolator/fuse hasn't tripped and that any room thermostat or programmer is calling for heat. 6) If the boiler shows other symptoms (unusual noises from the fan area, water ingress, damp smell), record them and switch off until an engineer attends.

Specific diagnostic and repair steps (for a qualified engineer only):

1) Safety isolate the appliance: switch off electrical supply and gas supply if required, follow lock-off procedures. 2) Remove the casing and visually inspect the fan and impeller for damage, foreign objects, or signs of water/moisture. 3) Manually check that the fan impeller spins freely; check bearings for wear. 4) Inspect the fan wiring harness and connector for loose pins, corrosion or damaged insulation; test continuity of the fan cable. 5) With safe procedures and correct test equipment, power the fan circuit and measure supply voltage/current and tachometer/signal to the control PCB to verify fan speed behavior against manufacturer spec. 6) Check the air pressure switch and its tubing for blockages or leaks, and verify the switch operation. 7) Inspect and clear the flue path and condensate drain; verify there is no water ingress into the fan housing. 8) Clean the fan assembly if contaminated (dust/debris) and re-test. 9) If the fan motor or bearings are faulty or if impeller damage is found, replace the fan assembly. 10) If wiring and fan are good but the control still reports incorrect speed, test and, if necessary, replace the PCB and restore service settings. 11) After any repair, reassemble, restore power and gas, run the appliance through several start/stop cycles to confirm stable operation and absence of the C6 216 error.

When to call a professional:

- If the initial reset does not clear the fault, or the fault returns, arrange a Gas Safe registered engineer. - If you are unable to identify an external blockage, or if there is any sign of water or electrical component damage, call a qualified engineer. - Any internal testing, wiring work, fan replacement, PCB replacement, flue work or gas-side interventions must be carried out by a Gas Safe registered engineer.

Emergency actions and notes:

- Do not continue to run the boiler when it is showing safety lockout codes. Repeated resets mask underlying hazards. - Keep records of the fault code, when it occurred and any actions taken; pass these to the attending engineer. - The C6 216 is a safety-related lockout; treat it seriously and get a qualified engineer to diagnose and repair rather than attempting major internal repairs yourself.