Chaffoteaux 607 Fault Code: Causes, Fixes & Repair Costs
What does the Chaffoteaux 607 fault code mean?
Fault code 607 (sometimes displayed as 6P1 on certain Chaffoteaux models) signals that the boiler's draught-proving system has detected inadequate airflow through the flue. In other words, combustion gases are not being expelled from the boiler efficiently enough for the unit to operate safely. The boiler's control board monitors flue draught continuously via a pressure sensor; when airflow falls below the required threshold, the boiler locks out and displays 607 to prevent potentially dangerous combustion conditions. This is categorised as a fan and flue fault and requires investigation before normal operation can resume.
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
- Blocked or obstructed flue terminal Common
The most frequent trigger for a 607 fault is a restriction at the flue outlet. Bird nests, accumulated debris, ice build-up in cold weather, or a crushed section of pipework can all reduce the airflow the boiler needs to prove draught. Even a partial blockage can be enough to trip the pressure sensor and lock the boiler out.
- Faulty or stuck PCB relay — fan runs continuously Common
On models such as the Chaffoteaux Inoa this is a well-documented and recurring issue. A relay on the control board can weaken and become stuck in the closed position, leaving the fan powered even when the boiler is off. When the boiler tries to start, the draught-proving sequence fails because the relay is not switching correctly. Left unattended, the stuck relay can overheat and damage the board beyond economical repair, making early diagnosis important.
- Fan motor failure Sometimes
The combustion fan is responsible for driving flue gases out of the heat exchanger and through the flue. If the motor windings have burned out or the bearings have seized, the fan cannot reach the speed required for adequate draught. The control board detects this shortfall via the pressure sensor and triggers a lockout.
- Faulty flue draught pressure sensor or blocked sensing tube Sometimes
A small plastic tube connects the pressure switch to the flue system. If this tube becomes kinked, partially blocked with condensate, or disconnected, the sensor will receive an inaccurate reading and report insufficient draught even when the fan is working correctly. Cleaning or reseating the tube has resolved the 607 fault in some reported cases.
- Excessive flue run or incorrect flue installation Rare
If the flue pipe is too long, has too many bends, or contains excessive horizontal sections, the natural resistance of the pipework can reduce draught below the boiler's minimum requirement. This is more likely to surface in older installations or after unauthorised modifications to the flue layout.
How to fix it
- Check your gas supply is working DIY safe
Confirm that other gas appliances in your home (hob, gas fire) are functioning normally. If there is no gas supply to your property, contact your gas supplier rather than investigating the boiler further.
- Visually inspect the external flue terminal DIY safe
From outside your home, look at the point where the flue exits the wall or roof. Check for obvious obstructions such as a bird nest, leaves, ice, or visible damage to the terminal grille. Do not attempt to access the roof or work at height unsafely. If you can see a clear blockage at ground-level reach and it is safe to do so, carefully remove it.
- Reset the boiler (up to twice) DIY safe
Once you have checked the above, attempt a boiler reset using the reset button or procedure described in your user manual. Wait a few minutes between attempts. If the boiler fires up and runs normally, monitor it over the next day or two. If the 607 fault returns promptly, do not keep resetting — further resets will not resolve an underlying mechanical fault and may mask a developing problem.
- Do not attempt to access internal components — call a Gas Safe engineer Gas Safe engineer
Diagnosing whether the fault lies with the PCB relay, the fan, or the pressure sensor requires dismantling the boiler casing and working on gas-connected components. This work is illegal for anyone who is not Gas Safe registered and carries serious safety risks. A qualified engineer will test the fan speed, inspect the pressure switch and sensing tube, check the PCB relay for signs of failure, and carry out a full flue integrity check.
- Engineer to inspect and clean the pressure switch sensing tube Gas Safe engineer
The Gas Safe engineer may find that the plastic tube running to the draught pressure switch is partially blocked with condensate or debris. Clearing and reseating this tube is a low-cost first step before moving on to component replacement.
- Engineer to test and replace the fan if required Gas Safe engineer
If the fan motor is found to be running below specification or has seized, it will need to be replaced with a compatible unit. Fan replacement on Chaffoteaux boilers typically covers both the motor assembly and any associated gaskets or seals.
- Engineer to diagnose the PCB relay and replace the control board if necessary Gas Safe engineer
If the stuck relay fault documented on the Chaffoteaux Inoa and related models is identified, the control board will need to be replaced. Acting promptly is worthwhile — a stuck relay that is left in place can overheat and cause more extensive board damage, increasing the overall repair cost.
Parts you may need
- Chaffoteaux flue fan / combustion fan assembly · from £130
- Flue draught pressure switch · from £35
- Pressure switch sensing tube / connector pipe · from £8
- Boiler PCB / control board · from £280
- Flue terminal and weather guard · from £25
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 £120–£380, depending on the underlying cause.
Frequently asked questions
What is the difference between fault code 607 and 6P1 on a Chaffoteaux boiler?
They refer to the same fault. Some Chaffoteaux models display the code as 607 while others — particularly those with a segment-style display — show it as 6P1. Both indicate insufficient flue draught detected by the pressure sensor, and the diagnostic and repair approach is identical for both.
Can I fix a Chaffoteaux 607 fault myself?
There is very little a homeowner can safely do beyond checking the gas supply is on, glancing at the external flue terminal for an obvious blockage, and attempting one or two resets. Any work inside the boiler casing — testing the fan, replacing the PCB, or working on the flue connections — must be carried out by a Gas Safe registered engineer. Attempting gas appliance repairs yourself is illegal and potentially dangerous.
How much does it cost to fix a Chaffoteaux 607 fault in the UK?
For the majority of homeowners, the repair will fall somewhere between £120 and £380 depending on what is found. A flue clean or pressure switch tube inspection at the lower end, fan replacement in the middle range (typically £220–£280 all-in), and PCB replacement at the higher end. If the PCB has been damaged by an overheating relay and requires an original Chaffoteaux board, the parts cost alone can push beyond £300, so acting quickly when the fault first appears can save money.
Why does my Chaffoteaux Inoa fan keep running when the boiler is switched off?
This is a known characteristic of the PCB relay fault associated with the 607 / 6P1 code on the Inoa. A relay on the control board becomes stuck in the on position, keeping the fan energised continuously. Beyond wasting electricity, the overworked relay can eventually overheat and cause irreversible damage to the board. If you notice the fan running constantly even with the boiler off, contact a Gas Safe engineer promptly rather than waiting for a full lockout to occur.