Worcester Bosch 228 fault code: what it means and what to do

A 228 fault on a Worcester Bosch boiler means the control system has detected a flame signal when no flame should be present. Worcester Bosch uses the wording “Flame signal without flame present” in official manuals for several ranges, including the Greenstar 1000, Greenstar 2000 and Greenstar 8000 Life.

This is a locking safety fault. It is not a code to investigate inside the boiler yourself.

What does Worcester Bosch fault code 228 mean?

The boiler continually monitors whether a flame is present. Code 228 indicates that the electronics received a flame-related signal at a time when the burner was not meant to be alight. The boiler locks out because it cannot safely continue until the cause has been checked.

The same code appears in more than one Worcester Bosch range, but the exact test sequence and component arrangement vary by model. An engineer should identify the full model and use the correct manufacturer instructions.

Is a 228 fault dangerous?

The code does not by itself prove that there is an active flame or gas leak. It does show that the boiler’s safety monitoring has detected an abnormal condition and stopped operation. Treat the lockout as a safety feature and do not try to bypass it.

If you smell gas, do not operate electrical switches or use a naked flame. Ventilate the property if it is safe, leave the area and call the National Gas Emergency Service on 0800 111 999. If a carbon-monoxide alarm sounds or anyone has symptoms such as headache, dizziness, nausea or confusion, move into fresh air and seek urgent help.

What might cause code 228?

An engineer may need to check the flame-monitoring circuit and related components. Depending on the model, the cause could involve the flame-sensing system, wiring, electrical interference, moisture or a control-board fault. These are examples of areas a qualified engineer may assess, not a list for homeowner testing.

The boiler casing must remain closed. Do not touch ignition or flame-sensing parts, test electrical components, adjust gas controls or attempt to dry internal components.

Can I reset a Worcester Bosch 228 fault?

Check the user manual for your exact model. If it expressly permits a user reset for this lockout, you may try that once. If 228 returns, the boiler will not reset, or the code appears repeatedly, stop and book a repair. Repeated resets do not remove the cause and can delay the correct safety check.

You can also confirm that the boiler has normal electrical power and that other gas appliances have not unexpectedly lost supply, provided there is no smell of gas. Do not use another appliance as a test if you have any safety concern.

What will an engineer do?

A Gas Safe registered engineer will confirm the boiler model, inspect the appliance in line with Worcester Bosch procedures and test the relevant safety and electrical systems. The repair depends on what those checks establish; the displayed number alone is not enough to identify a part that must be replaced.

Quick answer

Worcester Bosch code 228 means “Flame signal without flame present”. Keep the casing closed. Use a model-approved reset no more than once, then book a repair if the fault remains or returns.