Where is the reset button on a Worcester boiler?
The reset button on a Worcester boiler is on the control panel on the front, below or beside the display. You do not need to open anything to reach it. The exact control depends on which Greenstar you have, so check the model name on the front panel or on the label underneath before you start.
Worcester has used three styles of reset over the years. Dial and display models such as the Greenstar i, CDi and Si have a dedicated reset button. The Greenstar 4000 and the 8000 range use a full display with navigation keys, and the reset is a key combination rather than one button. A few older Worcester boilers use other controls, and the user instructions for your model show which one resets it.
Worcester boiler reset button by model
The table below is taken from the Worcester Bosch user instructions for each range. If your model is not listed, download the user instructions for it from the Worcester Bosch website using the name on the front of the boiler.
| Model | Reset control | How to use it | What a lockout looks like |
|---|---|---|---|
| Greenstar i (for example 25i and 30i ErP) | Reset button on the control panel, which also serves as the service engineer button | Press briefly once. The display shows Reset while it restarts | Blue light flashing and a fault code on the display |
| Greenstar CDi and Si (older display models) | Reset button on the control panel | Press it. When the reset works, the button goes out and the blue mains light stops flashing | Reset button lit and the blue mains light flashing, with a code on the display |
| Greenstar 4000 | No separate button; two keys on the display panel | Press the two keys shown in the user instructions until Reset appears. The boiler restarts and shows the flow temperature | A fault message with a coloured icon in the top right corner and a numbered code |
| Greenstar 8000 Life and Style | No separate button; two keys pressed together | Press the two keys shown in the user instructions together until the fault disappears | Fault code on the display |
The keys on the 4000 and 8000 panels are marked with symbols rather than words, so look at the diagram in your user instructions to find the right pair.
Worcester describes the reset as a brief press on dial and display models. Holding the button down for longer does not make the reset stronger, and on the Greenstar i the same button opens the service engineer functions.
How to reset a Worcester boiler
To reset a Worcester boiler, read the fault code first, deal with any obvious cause, then press reset once and give the boiler a few minutes to restart. Pressing reset without looking at the code throws away the one clue the boiler is giving you.
- Write down the code. Note the code and any text on the display. Our Worcester Bosch error codes page explains what each one means.
- Check the pressure. On a dial model the needle should be at 1 to 1.5 bar with the system cold. A low pressure code such as CE 207 will simply come back after a reset until the system is topped up, so follow our Worcester boiler pressure guide first.
- Check the gas. Make sure the gas hob or other gas appliances work and, if you have a prepayment meter, that it has credit. A boiler with no gas will fail to light and lock out.
- Check the condensate pipe in cold weather. If it has been freezing, a frozen condensate pipe outside is a common reason for a lockout. Our guide to a frozen condensate pipe shows how to thaw it safely.
- Press reset once. Use the button or key combination for your model from the table above.
- Wait and test. Give the boiler a few minutes to run its start sequence, then turn up the room thermostat or run a hot tap and listen for the burner lighting.
The Greenstar i user instructions say that if the reset is unsuccessful, the fault code reappears and the blue light keeps flashing. That is your signal that something needs fixing, not that the button needs pressing again straight away.
What a reset can and cannot clear
A reset clears a lockout, which is the boiler shutting itself down and waiting for someone to acknowledge the fault. It does not repair anything. If the cause has gone, such as a brief interruption to the gas supply or a pipe that has now thawed, the boiler will run normally. If the cause is still there, it will lock out again.
Not every code can be reset. The Greenstar i user instructions note that some fault codes cannot be cleared by a simple reset because of the boiler's internal safety systems, and in that case you need to contact Worcester Bosch or an engineer. Other codes, such as low pressure warnings, clear by themselves once the cause is dealt with.
| Code | What it means | Before you press reset |
|---|---|---|
| EA 227 | No flame detected on ignition | Check the gas supply and meter credit |
| EA 229 | Flame lost during operation | Check the condensate pipe in cold weather |
| CE 207 | Low system pressure | Top up to 1 to 1.5 bar first |
| E9 224 | Overheat thermostat operated | Check the pressure and that radiator valves are open |
| A1 281 | Pump problem or air in the system | Check the pressure; do not keep resetting |
How many times can I reset my Worcester boiler?
Reset a Worcester boiler once, and if it locks out again, try at most once or twice more after checking the pressure, gas and condensate pipe. Leave a few minutes between attempts. If the same code comes back after two or three resets, stop: the fault is real and a Gas Safe registered engineer needs to find it.
Worcester's instructions describe a single press, not repeated attempts. A lockout is a safety response. The boiler has seen something it does not like, such as no flame, too much heat or too little water, and repeated resets only make it try again under the same conditions. For general advice that applies to any make, see our guide on how to reset a boiler.
Never remove the boiler casing to look for the cause of a lockout. The gas valve, burner, fan and electrical parts are inside, and only a Gas Safe registered engineer should work on them. If you smell gas, do not press reset or operate switches: turn off the gas at the meter if you can, open windows and call the National Gas Emergency Service on 0800 111 999.
Why does my Worcester boiler keep locking out?
A Worcester boiler that keeps locking out usually has a problem with the gas supply, the condensate drain, the water pressure or a component that lights and monitors the flame. The code tells you which area to look at.
Gas supply problems
Low or interrupted gas stops the burner lighting, which shows as an ignition code such as EA 227. Common causes are a prepayment meter out of credit, a gas valve partly closed after other work, or a problem with the supply to the property. If the hob also struggles, contact your gas supplier. Our guide to a boiler not firing up goes through ignition faults in more detail.
Condensate pipe blocked or frozen
Every Greenstar is a condensing boiler, so it drains acidic water through a plastic pipe, often to an outside drain. If that pipe freezes or blocks, the water backs up and the boiler shuts down. Lockouts that start on the first cold night of the year and clear when the weather warms point to this.
Pressure and circulation
A system that keeps losing pressure will keep causing low pressure lockouts, and poor circulation from air, sludge or a failing pump can lead to overheat codes. Topping up is a homeowner job, but a pressure that keeps dropping means there is a leak to find.
Worn or dirty components
An ignition electrode that has worn, a flame sensing problem, a fan fault or a flue issue can all cause repeated lockouts. These parts are inside the sealed case, and an annual service is when an engineer normally checks them.
When to call a Gas Safe registered engineer
Call Worcester Bosch customer support, your installer or a Gas Safe registered engineer if the boiler locks out again after two or three resets, if the code is one the user instructions say you cannot reset, or if lockouts keep happening even though the boiler runs for a while after each reset. If your boiler is still under its Worcester guarantee, contact Worcester first, because repairs by someone else may affect the cover.
Before you call, note the model name, the exact code, how often it has happened and what you have already checked, such as the pressure reading and whether other gas appliances work. That helps the engineer arrive with the right parts. For a general idea of what repairs cost, see our guide to boiler repair costs.