How to reset your Baxi boiler
Most Baxi boilers have a red reset button on the front of the unit, usually near the bottom. Press and hold it for about 10 seconds, then release. The boiler will attempt to restart and should fire up within a few seconds if the fault has cleared. If the boiler lights but the reset button pops out again within a few minutes, there is an underlying problem that the reset cannot fix — stop trying to reset and call a Gas Safe engineer instead.
The reset button exists because boilers shut themselves down as a safety measure when they detect certain faults — a flame failure, low water pressure, or a blocked flue sensor. A single reset is fine. Repeated resets mean the boiler is detecting a real fault each time, and pushing the button again will not solve it.
If your boiler has no visible red button, check the manual or the manufacturer's label on the unit itself — some Baxi models use a different reset method, such as turning a dial or holding down a button combination. The manual will also tell you which faults can be reset and which require an engineer.
Key Takeaways
- The red reset button on the front of most Baxi boilers restarts the unit after a safety shutdown, but only works if the underlying fault has cleared.
- If the reset button pops out again within minutes, the boiler is detecting a real fault — repeated resets will not fix it and you need to call a Gas Safe engineer.
- Some Baxi models use a dial or button combination instead of a red button, so check your manual or the label on the boiler itself.
- A boiler that needs resetting more than once a week is telling you something is wrong and should be inspected by a professional.
Why your Baxi boiler shuts down and locks out
A boiler lockout is a safety feature. When the boiler detects that the flame has gone out, the water pressure has dropped below safe operating level, or the flue sensor is blocked, it stops burning fuel and waits for a reset. This prevents the boiler from pumping unburned gas into your home or running without water circulation.
The most common reason for lockout is a blocked flue sensor — a small tube that checks whether the flame is burning. Dust or condensation can block it, causing the boiler to think the flame has failed. Low water pressure is the second most common cause. If your pressure gauge (usually on the front of the boiler) reads below 1 bar, the boiler will lock out. A one-time reset after topping up the pressure is normal; repeated lockouts after pressure top-ups mean you have a leak somewhere in the system.
When a reset will work and when it won't
A reset works when the fault was temporary — a brief flame failure caused by a gust down the flue, or a pressure dip that you have now corrected. After you reset, the boiler should stay running. If it locks out again within an hour, the fault is still present and a reset will not help.
Do not keep pressing the reset button hoping it will eventually stick. Each lockout is the boiler telling you something is wrong. Repeated resets can damage the boiler's ignition system over time and waste gas. If your boiler is locking out more than once a week, or if it locks out when ready after you reset it, contact a Gas Safe registered engineer. They can diagnose whether the fault is a blocked sensor, a pressure leak, a faulty ignition electrode, or something else.
How to check water pressure before resetting
Look at the pressure gauge on the front of your boiler — it is usually a small dial with a needle or a digital display. The safe operating range is between 1 and 2 bar (some boilers show 1.5 bar as the ideal). If the needle is below 1 bar, the boiler will lock out.
To raise the pressure, locate the filling loop — a flexible hose with two small valves, usually under the boiler or at the base of the unit. Open both valves slowly until the pressure gauge rises to 1.5 bar, then close them again. You should hear water flowing through the hose while the valves are open. If no water flows, the filling loop may be blocked or disconnected, and you will need an engineer to refill the system.
After you have raised the pressure, wait a few minutes for the boiler to settle, then press the reset button. If the boiler stays running, the pressure drop was the problem. If it locks out again within an hour, you have a leak in the system and should call an engineer.
Checking the flue for blockages
The flue is the pipe that carries exhaust gases out of your home. If it is blocked by bird nests, leaves, or snow, the boiler will lock out as a safety measure. Look outside your home to find where the flue exits — it is usually a white or grey plastic pipe coming out of a wall or roof.
Check that the opening is clear and not covered by debris. If you see a blockage you can safely reach, remove it. Do not climb onto the roof or use a ladder unless you are confident doing so — if the blockage is out of reach, call an engineer. After clearing the flue, wait a few minutes and press the reset button.
If the boiler locks out again and the flue is clear, the problem is likely the flue sensor itself, which sits inside the boiler. This cannot be cleared without opening the boiler, so you will need an engineer.
When to call a Gas Safe engineer instead of resetting
Call an engineer when ready if the reset button does not stay in, if the boiler locks out within minutes of resetting, or if it locks out more than once a month. Also call if you smell gas, hear unusual noises from the boiler, or see water leaking from underneath it.
You should also have an engineer visit if you have reset the boiler more than three times in the past year. Repeated lockouts mean the boiler is developing a fault, and resetting it repeatedly can cause further damage. An engineer can identify the root cause — a faulty ignition electrode, a worn pump, a blocked heat exchanger, or a pressure relief valve that is leaking — and fix it properly.
All boiler repairs must be done by a Gas Safe registered engineer. You can find one through the Gas Safe Register website or by asking your boiler manufacturer for a list of approved engineers in your area. Keep the engineer's receipt and any work notes for your records.
Preventing lockouts in the future
Have your boiler serviced once a year by a Gas Safe engineer. During a service, they will clean the flue sensor, check the ignition electrode, test the pressure relief valve, and make sure all seals are intact. A boiler that is serviced regularly locks out far less often.
Check your boiler's pressure gauge every few months. If it drops below 1 bar between services, you have a slow leak somewhere in the system — it may be in a radiator valve, a pipe joint, or the boiler itself. A slow leak will eventually cause the boiler to lock out, so have it found and repaired before that happens.
Keep the area around your boiler clear of dust and debris, and make sure the flue opening outside is not blocked by vegetation or weather. These straightforward checks can prevent many of the faults that trigger lockouts.
Frequently Asked Questions
What does the reset button actually do?
The reset button tells the boiler to try lighting the flame again. It does not fix the underlying problem — it just gives the boiler a chance to restart. If the fault is still there, the boiler will lock out again when ready or within a few minutes.
Is it dangerous to keep pressing the reset button?
It is not when ready dangerous, but it can damage the boiler over time. Each reset attempt uses the ignition system, and repeated attempts can wear out the ignition electrode faster. If your boiler needs resetting more than once a week, stop resetting it and call an engineer instead.
Can I reset my boiler if the pressure is low?
You can, but it will lock out again when ready. Raise the pressure to 1.5 bar using the filling loop first, then reset. If the pressure drops again within a few hours, you have a leak and need an engineer.
How long does it take for a boiler to restart after a reset?
The boiler should light up and start heating water within 10 to 30 seconds of pressing the reset button. If nothing happens after a minute, press the button again or call an engineer — the boiler may have a fault that prevents it from restarting.
Will resetting my boiler clear an error code?
A reset will clear the lockout and stop the error code from showing, but only if the fault has actually gone away. If the fault is still present, the error code will return as soon as the boiler tries to restart. Check your manual to see what each error code means — some codes require an engineer visit regardless of whether a reset works.