Error 212

Safety precautions:

1. If you smell gas or suspect a gas leak, leave the property immediately and call the gas emergency number. Do not operate electrical switches or the boiler.

2. If the boiler has shut down and the case or flue feels very hot, allow it to cool before touching. Isolate boiler power at the fused spur or consumer unit if you need to for safety.

3. Do not remove covers, access internal components, or attempt gas or sealed system repairs yourself. Only a Gas Safe registered engineer should open the boiler casing and work on gas or heat-exchanger components.

Initial homeowner checks you can safely do:

1. Note exactly when the fault occurred and whether any other symptoms happened first (strange noises, loss of pressure, radiators not heating, unusual smells).

2. Check the system pressure on the boiler gauge. If pressure is below about 1.0 bar, re-pressurise the system following the boiler user manual to bring pressure to around 1.0–1.5 bar and then try a single reset. Low pressure can cause sensors to behave oddly.

3. Reset the boiler once only: switch off using the boiler controls or the on/off switch, wait 30 seconds, then switch on. If the fault clears and the boiler runs normally, monitor for recurrence. Do not keep resetting repeatedly.

4. Listen and look: with the boiler calling for heat, check whether the heating pump runs (you may hear or feel vibration from the pump or flow pipes). Check whether radiators heat across top to bottom (cold tops with warm bottoms can indicate sludge/blockage).

Specific diagnostic checks and basic fixes you can perform:

1. Check for obvious circulation problems: bleed a couple of radiators (air in the system can cause poor circulation). After bleeding, recheck system pressure and top up if needed.

2. If radiators are cold or the pump appears silent, try gently feeling the pipework near the pump and the flow and return pipes when the boiler is calling for heat. If the pump is not running and you can confirm the boiler is trying to fire, leave the appliance off and call an engineer—do not force or try to dismantle the pump.

3. If the fault happened after a long period of inactivity or following work on the system, an airlock is possible. Bleeding radiators and ensuring correct system pressure is the safe first-line action.

4. Avoid repeated resets. If the 212 error returns after a single reset, switch the boiler off and leave it off until inspected by an engineer.

When to call a professional and what they will check:

1. Call a Gas Safe registered engineer if the fault persists after the basic checks, if the pump appears faulty, if radiators show signs of sludge, or if the boiler repeatedly trips with 212. This fault can require replacement of sensors (flow thermistor or safety thermostat), replacement or repair of the safety temperature limiter, pump replacement, removal of scale from the heat exchanger, or electrical/wiring repairs.

2. The engineer will run controlled diagnostics: check sensor readings and wiring, perform pump tests, check flow/return temperatures, examine the heat exchanger for scale or blockages, and confirm whether the safety limiter has tripped and needs replacing.

3. Do not ask the engineer to reset repeatedly as a permanent fix; the root cause must be found and repaired to avoid unsafe conditions.

Final notes:

1. The boiler’s automatic shutdown is a safety feature — it prevents overheating but also signals a problem that should not be ignored if it recurs.

2. If you are unsure at any stage, or if symptoms look like overheating, loss of gas, or repeated lockouts, leave the boiler off and arrange an engineer visit. Only a Gas Safe registered engineer should carry out internal repairs, sensor replacements or work on the gas and sealed water system.