Worcester Bosch boiler fault codes

Unfortunately, even the best boilers can run into problems, no system is perfect, including those from Worcester Bosch.  Boilers consist of many mechanical and electrical parts and if any of these fail, the boiler will tell you by displaying a fault code to alert you to the problem.

In this page we have compiled a list of the most common Worcester Bosch boiler fault codes and will try to help you determine whether you can resolve the issue yourself or if you’ll need help from a professional heating engineer.

Ok, before we start ‘Safety First’

Remember, safety is paramount.  Never attempt to open or tamper with your boiler.  All repairs inside your boiler should only be completed by a qualified Gas Safe Engineer.  Addressing boiler issues correctly ensures the safety of your home and can prevent further damage to the unit.

Understanding Worcester Bosch boiler fault & error codes

Worcester Bosch boilers display specific fault codes on your boilers front panel.  These codes help in diagnosing issues efficiently, ensuring faster repairs.  Here’s how these fault codes are categorized on a Worcester boiler:

• Locking Error: Indicates a major fault requiring immediate attention.  The boiler will show a flashing fault code accompanied by a triangle and a static cause code.  Resetting the boiler is necessary after the fault is rectified.
• Blocking Error: When the boiler stops functioning and powers out without displaying a code.  Press the return button to view the code.  The error clears once the fault is addressed.
• Fault Error: Displayed as a letter and a number code, indicating a specific fault within the boiler system.
• Maintenance Code: Begins with an ‘H’, signaling that the boiler needs servicing but can still operate temporarily without immediate repair.
• Cause Error: A three-digit number that helps in further diagnosing the fault during blocking or locking errors.

Most common Worcester Bosch fault codes and solutions

We’ve presented our list of common boiler fault codes & error codes by type of boiler and we hope that makes it easier for you!

1. Greenstar i System & Combi Boiler error codes:

• FD: Power interrupted – check your home’s electrical connections.
• EA: No ionisation detected after ignition – inspect for gas supply issues or electrode faults.
• E9: High primary flow temperature – potential circulation or thermostat issues.
• A1: Pump stuck or running dry – may involve re-filling the boiler system with water or checking for leaks.

2. Greenstar Si Compact Boiler fault codes:

• T1-T6: Various component tests – these indicate specific testing protocols for components like ignition, fan, and pumps.

• EA fault code: No flame detected – like the Greenstar i, this could be due to gas supply problems.

3. CDi Classic Regular/Combi Boiler fault codes:

• C6: Fan speed too low or high – fan issues might need adjustments or replacement.

• F7: Flame detected post shutdown – a serious safety issue possibly linked to a faulty flame sensor or control board.

4. CDi Highflow Boiler error codes:

We see quite a few Worcester CDi fault codes, particularly with the 30CDi.  Here are some of the common ones:

• D5: Condensate pump failure – ensure the pump is clear of blockages, particularly during cold weather.

• E9: Safety temperature limiter tripped, check for overheating causes.

5. Greenstar Worcester 8000 fault codes (both the ‘Life’ and ‘Style’ boilers):

The Worcester 8000 fault codes that we see often include:

• 200-204: Operational modes indicating specific states such as heating mode or standby.

• 227 V: No flame signal – might require replacements of burner control unit or sensors.

What to do if you see a fault or error code on your boiler

1. Identify the Code: Match the code displayed on your boiler with those listed in this guide.
2. Basic Troubleshooting: Some issues, like resetting the boiler or checking your boiler pressure, can be handled if you’re confident in following safety procedures.
3. Contact a Professional Gas Safe Engineer: For boiler faults involving gas or electrical parts, always contact a certified Gas Safe Registered Engineer.

Our 2 Top Tips to prevent your boiler breaking down

1. Boiler Servicing: Getting your boiler serviced annually can help limit faults occurring and is a great way to increase the lifespan and efficiency of your boiler.  Boiler service plans are a great way to take the hassle out remembering to book your boiler service.
2. Chemical Treatments: Every 2-3 years, we recommend chemically treating your boiler system (think of this as similar to doing an oil change on your car).  This involves draining your boiler system water out and flushing it through with cleaning chemicals.  Then refilling your boiler system with clean fresh water and finally adding chemical inhibitors to help prevent the build up of corrosion inside your boiler system.  In our experience poor water quality is the number 1 reason why boilers breakdown.

Summary & next steps

Worcester Bosch boiler fault codes and error codes are designed to help you quickly diagnose issues within your boiler heating system.  Knowing what these fault codes actually mean should help you determine if you need to call a boiler repair engineer out.

Is it time for a new boiler?

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Get in Touch: For straightforward, professional help with your Worcester Bosch boiler, the Celsius team are here to help:

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