Error C6 215

Safety first

- If you smell gas or suspect carbon monoxide (headaches, nausea, dizziness, visible soot, pilot light issues), immediately turn off the gas supply at the meter (if safe to do), turn off the appliance, evacuate the property and call the gas emergency number and/or 999. Do not use electrical switches or open flames. Get fresh air and do not re-enter until it is safe.

- If the boiler is locked out repeatedly with the same fault, do not keep resetting and running it. Persistent fan/flue faults are safety issues and the appliance should be isolated until repaired.

- Always isolate electrical supply before attempting any physical checks that require access to the boiler. Do not remove sealed panels or perform internal repairs unless you are qualified.

Initial homeowner checks (safe, straightforward steps)

1. Note the exact fault code (C6 215), date/time, and any symptoms (lost heating/hot water, unusual noises, water near flue). Take a photo of the display and the boiler rating/serial label — this helps the engineer.

2. Try a controlled reset: press and hold the reset or ✔ button for about 8 seconds until the boiler reboots. If the fault does not return, monitor for recurrence. If it reappears, stop trying repeated resets.

3. Power-cycle the boiler: switch off at the isolator or fuse spur, wait 30 seconds, then restore power and try a restart.

4. Check the external flue outlet (outside wall/roof): make sure the terminal is clear of leaves, debris, bird nests, snow or ice and that nothing is blocking air flow. Clear only external debris you can reach safely from the ground or with safe access.

5. Check condensate drainage: inspect external condensate pipe for frost/blockage or water freezing in cold weather. A blocked/iced condensate can cause abnormal behaviour. If you suspect frozen condensate, thaw it safely (warm water from a container) but do not use open flame or excessive heat on pipes.

6. If the boiler sits where you can see any accessible external wiring/plug to flue accessories, visually check for obvious damage or disconnected plugs. Do not open the boiler casing.

If the above do not clear the fault

- Do not attempt internal electrical/mechanical repairs yourself. The next steps require a qualified engineer:

- An engineer will inspect the fan harness and connector (this is a common fault point), verify correct supply voltage at the fan, and test the fan’s response to control signals from the PCB.

- They will check the fan impeller for smooth free rotation and examine bearings for wear or seizure. Moisture, dust or foreign objects can impair the fan.

- The air pressure switch and its tubing will be inspected for blockages or leaks; an incorrect pressure signal can cause fan-speed errors.

- The engineer will test the PCB outputs and sensors; if control electronics are faulty they will isolate whether the fan, the harness, or the PCB is at fault.

- If required the engineer will replace the fan assembly or any faulty wiring or control board components and then verify correct fan speed and safe flue flow.

Prepare for the engineer visit

- Have the boiler model, serial number, age, fault code (C6 215) and a short history (when it started, any recent work or power issues, whether you reset it) ready. Photos of the flue terminal and any visible damage help diagnosis.

- Check warranty and service history before the engineer call; some repairs may be covered by manufacturer warranty or service contracts.

Final notes

- Because the fan and flue system are critical to safe combustion and exhaust of gases, fixing a C6 215 fault is a job for a competent, Gas Safe registered engineer. Only they should carry out wiring tests, fan replacement, PCB work or internal inspections. Avoid running the boiler if the fault persists; isolate it and arrange a professional repair.