Chaffoteaux 416 Fault Code: Causes, Fixes & Repair Costs
What does the Chaffoteaux 416 fault code mean?
The 416 fault code (sometimes displayed as '4 16') on a Chaffoteaux boiler most likely indicates a fan or air pressure switch fault — meaning the boiler's control system has detected a problem with the flue fan circuit or has failed to receive the expected confirmation signal from the air pressure switch. On some Chaffoteaux models the display shows fault codes as two separate numbers (a functional-unit digit followed by a fault number), so '4 16' and '416' are typically the same code read from the same screen. Because Chaffoteaux code structures vary across model ranges — including the Pigma, Talia, Urbia, and Expert Control — the precise trigger can differ slightly between boilers, but the fan and air pressure switch circuit is the consistent common thread. If the boiler cannot confirm adequate airflow through the flue, it will shut down as a safety measure to prevent combustion gases from remaining inside the appliance.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- Faulty or seized fan motor Common
The fan is responsible for expelling combustion gases through the flue. If the motor wears out, seizes, or fails to reach the correct speed, the air pressure switch never receives the signal it needs and the boiler locks out. Fan failure is the single most common cause of this type of fault across the Chaffoteaux range.
- Split, blocked, or kinked air pressure switch tubing Common
A small silicone or rubber hose connects the fan housing to the air pressure switch. Over time this tube can crack, collapse, or become blocked with condensation residue. Even a pinhole split means the pressure switch registers no airflow, triggering the fault even when the fan itself is working perfectly.
- Faulty air pressure switch Sometimes
The air pressure switch is a small diaphragm device that confirms airflow is present before allowing ignition. The diaphragm can harden or split with age, or the electrical contacts can fail, causing the switch to report no airflow regardless of what the fan is doing.
- Blocked or partially obstructed flue Sometimes
A flue terminal blocked by a bird's nest, debris, or ice can create back-pressure that prevents the fan from moving air efficiently. In this situation the fan may be running but the pressure switch still does not close because effective airflow through the system is insufficient.
- Frozen condensate pipe Sometimes
In cold weather a blocked or frozen external condensate pipe can cause a pressure build-up that mimics an airflow fault and triggers a lockout. This is worth checking before calling an engineer, particularly in temperatures below about 2°C.
- PCB fault Rare
The printed circuit board controls the fan circuit and interprets the signal from the air pressure switch. If the PCB develops a fault — whether through age, a power surge, or a failed component elsewhere overloading it — it may misread the fan circuit or fail to drive the fan at all. This is less common but worth investigating if the fan and switch both test as healthy.
How to fix it
- Reset the boiler once DIY safe
Locate the reset button on your Chaffoteaux boiler (usually a button or rotary control marked with a flame or reset symbol). Press it once and wait up to two minutes for the boiler to attempt a restart. If the fault clears and stays clear, monitor the boiler over the next hour. If the 416 code returns, do not reset more than two or three times in total — repeated resets without a fix can mask a worsening problem.
- Check the external condensate pipe for freezing DIY safe
In cold weather, locate the white plastic condensate discharge pipe that exits through an outside wall, usually at low level. If it feels solid or you can see ice around the outlet, it is likely frozen. You can carefully pour warm (not boiling) water over the external section to thaw it, or wrap it with a warm damp cloth. Once thawed, reset the boiler. Consider insulating the pipe to prevent a recurrence.
- Check the flue terminal outside for obvious blockages DIY safe
From outside (without ladders or accessing the roof unless it is safe and level), look at the flue outlet — typically a plastic or metal terminal on a wall or roof. Check for visible debris, a bird's nest, or anything physically blocking the opening. Do not attempt to dismantle the flue yourself; if you spot a blockage inside the terminal or in the flue run, report this to your engineer.
- Verify the gas supply is on DIY safe
Confirm that your gas meter is on and that other gas appliances in the property (such as a hob) are working normally. If you suspect a gas supply interruption, contact your gas supplier. Do not attempt any internal work on the boiler's gas circuit.
- Engineer to inspect and test the fan motor Gas Safe engineer
A Gas Safe registered engineer will check that the fan is receiving the correct electrical supply from the PCB and measure whether the motor is running at the correct speed. A fan that is drawing excessive current, running slowly, or failing to start will need to be replaced with a compatible Chaffoteaux part.
- Engineer to inspect the air pressure switch tubing and switch Gas Safe engineer
The engineer will check the silicone hose between the fan and the air pressure switch for splits, kinks, or blockages, and test the switch itself for correct operation. A faulty tube is an inexpensive fix; a failed switch is a straightforward replacement for a qualified engineer.
- Engineer to check the flue for back-pressure or partial blockage Gas Safe engineer
Using appropriate tools, the engineer will verify there are no internal flue restrictions causing back-pressure that prevents the pressure switch from operating correctly. Any internal flue obstruction must be cleared before the boiler is returned to service.
- Engineer to test PCB outputs and wiring to the fan circuit Gas Safe engineer
If the fan and air pressure switch are both in good condition, the engineer will test whether the PCB is sending the correct voltage signals. Wiring harnesses can suffer from corrosion or loose connectors over time. The PCB itself will only be replaced if all other components test as healthy, since it is a higher-cost repair.
- Call a Gas Safe registered engineer if the fault persists Gas Safe engineer
If your own checks (reset, condensate pipe, flue terminal, gas supply) have not resolved the fault, arrange for a Gas Safe registered engineer to carry out a full fan circuit diagnosis. Provide them with your exact boiler model and the precise code displayed — including whether it shows as '416' or '4 16' — so they can cross-reference it with your model's specific documentation before attending.
Parts you may need
- Flue fan / fan motor assembly · from £145
- Air pressure switch · from £35
- Air pressure switch tubing / hose · from £8
- PCB (printed circuit board) · from £220
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £150–£380, depending on the underlying cause.
Frequently asked questions
Is fault code 416 the same as '4 16' on a Chaffoteaux boiler?
Almost certainly yes. Chaffoteaux boilers structure their fault codes using a functional-unit digit followed by a fault number, and the display often separates these with a space or a short pause. A homeowner reading the display quickly may see this as the single number '416'. Both refer to the same fault in the fan or air pressure switch circuit. If you are unsure, note the exact model of your boiler and check the relevant section of its manual, or mention both '416' and '4 16' when you speak to your engineer.
Can I fix a Chaffoteaux 416 fault myself?
There are a few safe checks you can carry out yourself: resetting the boiler (up to two or three times), thawing a frozen condensate pipe in cold weather, and checking the external flue terminal for obvious debris. Beyond that, all internal work — including testing or replacing the fan, air pressure switch, tubing, or PCB — must be carried out by a Gas Safe registered engineer. Attempting internal boiler repairs without Gas Safe registration is illegal and potentially dangerous.
How much does it cost to fix a Chaffoteaux fan fault in the UK?
Most homeowners pay somewhere between £150 and £380 all-in for a fan or air pressure switch repair, including the engineer's call-out and labour. Replacing just the air pressure switch hose is at the lower end; a full fan motor replacement typically falls in the £220–£350 range once parts and an hour or two of labour are factored in. PCB replacement is a more expensive outlier — typically £400–£600 including parts and labour — and is only needed when all other components have been ruled out. If your boiler is over 10–12 years old and needs a PCB or fan assembly, it is worth getting a boiler replacement quote at the same time to compare costs.
Why does my Chaffoteaux boiler keep coming back to 416 after I reset it?
A fault that returns after resetting almost always means the underlying cause has not gone away. The boiler is detecting the same problem — most likely with the fan not reaching the correct speed, the air pressure switch not closing, or a flue obstruction — and locking out again as a precaution. Repeatedly resetting without a repair does not fix anything and may delay diagnosing a problem that will only get worse. Limit resets to two or three attempts, then arrange for a Gas Safe engineer to investigate.