Main E160 Fault Code: Causes, Fixes & Repair Costs
What does the Main E160 fault code mean?
The E160 code on a Main boiler indicates that the boiler's control system has detected a problem with the flue fan — either it isn't spinning at all, or it's failing to reach and maintain the correct operating speed. As a safety measure, the boiler locks out and stops firing until the fault is resolved. The fan plays a critical role in safe combustion: it draws fresh air into the burner and pushes combustion gases out through the flue. Without it working correctly, harmful gases could accumulate, so the boiler is right to shut itself down. Note that Main is a brand within the Baxi Group, and E160 carries the same meaning across all Baxi Group boilers — so if you have a Baxi, Potterton, or similar model showing E160, the same diagnosis and repair approach applies.
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 worn fan motor Common
The fan motor is the most common culprit for E160. Over years of continuous cycling, the motor bearings wear down, the motor windings can degrade, or the impeller becomes clogged with dust and debris. When the motor can no longer reach the correct speed — or stops spinning entirely — the boiler's airflow sensor detects the problem and triggers a lockout. Boilers that haven't been serviced regularly are especially prone to this.
- Blocked flue terminal or air intake Common
If the external flue terminal — the plastic outlet usually visible on an outside wall — becomes obstructed by leaves, bird nests, spider webs, or accumulated grime, airflow is restricted. The fan then struggles to maintain the correct pressure differential, and the boiler shuts down with E160. UK boilers with rear-exit or low-level flues are particularly vulnerable, especially after autumn or windy weather.
- Wiring or electrical connection fault Sometimes
The fan relies on a set of wires connecting it to the PCB for both power and feedback signals. If any of these connections become loose, corroded, or chafed — which can happen through normal vibration over time — the fan may not receive power or may not send back a reliable speed signal. This can cause intermittent faults where the boiler runs briefly then locks out again.
- Faulty air pressure switch Sometimes
The pressure switch confirms to the PCB that the fan is generating sufficient airflow before allowing ignition. If the switch's diaphragm has perished, or the small rubber tube connecting it to the fan housing is cracked or blocked, the boiler may lock out with E160 even when the fan itself is perfectly healthy. This is a relatively inexpensive component but requires an engineer to diagnose and replace.
- PCB (printed circuit board) failure Rare
The PCB controls and monitors the fan's operation. If it has suffered a fault — through a power surge, moisture ingress, or simple age — it may either fail to send the correct power signal to the fan, or misread the fan's speed feedback and trigger a spurious lockout. PCB faults tend to produce persistent or erratic error codes that don't respond to other repairs.
How to fix it
- Check your gas supply is working DIY safe
Before assuming the fault lies with the boiler itself, quickly confirm that your gas supply is live. Check that other gas appliances in your home — such as the hob or gas fire — are working normally. If there's a wider gas supply issue, contact your gas supplier rather than focusing on the boiler.
- Look and listen when the boiler tries to start DIY safe
When you call for heat, stand near the boiler and listen carefully. A healthy fan produces a clear, steady hum before ignition. If you hear nothing, a grinding or rattling noise, or only a brief whirr before the boiler locks out, this points strongly towards a fan motor problem. Note what you observe and pass this information to the engineer — it will help speed up diagnosis.
- Inspect the external flue terminal for obvious obstructions DIY safe
Locate the flue outlet on the outside of your property — it's usually a round plastic fitting on an external wall. Check whether it's visibly blocked by leaves, a bird nest, frost, or other debris. If you can safely reach it from ground level and there is a clear external blockage, you may be able to carefully remove it. Do not probe inside the flue or dismantle any fittings.
- Reset the boiler once or twice DIY safe
Press and hold the reset button (refer to your boiler's user guide for the exact location — it's often marked with a flame symbol or the word 'Reset') for around three seconds. Allow the boiler a full minute to attempt a restart. If it fires up and runs normally, monitor it over the next few hours. If the E160 code returns promptly, do not continue resetting — repeated resets without resolving the underlying cause can cause further damage.
- Do not attempt to access internal fan components yourself Gas Safe engineer
The fan, pressure switch, wiring harness, and PCB are all located inside the boiler casing and are not user-serviceable. Removing the boiler casing and working on internal components requires Gas Safe registration. Attempting this yourself could invalidate your warranty, cause further damage, and potentially create a safety hazard.
- Call a Gas Safe registered engineer to diagnose and repair the fault Gas Safe engineer
An engineer will remove the casing safely, test the fan motor speed electronically, inspect the wiring and connectors, check the pressure switch and its associated tubing, and assess the PCB. They'll carry out the appropriate repair — whether that's clearing a blockage, replacing the fan motor, renewing a faulty pressure switch, or repairing wiring — and then run a full functional test before leaving. If your boiler is still under manufacturer's warranty, mention this when booking, as the repair may be covered.
Parts you may need
- Boiler fan motor (Baxi/Main compatible) · from £85
- Air pressure switch · from £35
- Fan wiring harness · from £25
- 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 £120–£350, depending on the underlying cause.
Frequently asked questions
Is E160 on a Main boiler dangerous?
The E160 code itself isn't immediately dangerous — the boiler has safely locked itself out precisely to prevent a hazardous situation from developing. However, you shouldn't attempt to repeatedly override the lockout or tamper with the fan assembly. Get a Gas Safe engineer to diagnose and fix the root cause promptly, particularly if the fan was running abnormally before the lockout.
Can I fix the E160 fault myself?
There are a couple of safe checks you can carry out yourself: confirming your gas supply is on, looking for an obvious blockage at the external flue terminal, and resetting the boiler once or twice. Beyond that, the repair requires a Gas Safe registered engineer. Working on the fan motor, wiring, pressure switch, or PCB without the appropriate qualifications is unsafe and would likely void your boiler warranty.
Why does my Main boiler keep coming back with E160 after I reset it?
If the fault returns quickly after each reset, it's a strong signal that there's a genuine mechanical or electrical problem rather than a one-off glitch. The most likely culprits are a worn fan motor that can no longer sustain the correct speed, a faulty pressure switch that isn't confirming airflow, or a wiring issue causing an intermittent loss of signal. Stop resetting and book an engineer — persistent resets without a fix can cause additional wear.
How much does it cost to fix E160 on a Main boiler?
For most homeowners, the repair falls between £120 and £350 including parts and labour. A straightforward fix such as clearing a blocked flue terminal or replacing a pressure switch sits at the lower end; a fan motor replacement typically costs £180–£300 all-in. PCB replacement is less common but significantly more expensive — often £350–£500 depending on the model — and if both the fan and PCB need replacing simultaneously, costs can exceed £500. An engineer will be able to give you a firm quote once they've diagnosed the specific fault.
Does the E160 code mean the same thing on Baxi and Potterton boilers?
Yes. Main is part of the Baxi Group, and E160 means a fan fault across all brands in the group — including Baxi and Potterton. The diagnosis and repair process is essentially identical regardless of which brand name is on the front of the boiler, as many of these models share the same internal components and control systems.