Worcester Bosch Boiler Error Codes: Comprehensive Guide and Solutions

If your Worcester Bosch boiler is showing an error code, it’s signaling that something isn’t working correctly. Error codes, also known as fault codes, are designed to help diagnose and troubleshoot problems efficiently. This guide provides a detailed list of common Worcester Bosch boiler error codes, helping you understand what’s wrong and whether you need professional assistance.

Understanding Worcester Bosch Boiler Error Codes

Worcester Bosch boilers are equipped with advanced diagnostic systems that trigger error codes when something goes wrong. Here’s how these codes are categorized:

• Locking Error: The boiler will display a flashing fault code, usually accompanied by a triangle symbol. This locks the system until the issue is resolved.
• Blocking Error: The boiler powers down without displaying a fault code. You need to press the return button to view the code.
• Fault Error: A visible alphanumeric code is displayed, indicating a specific issue that requires attention.
• Maintenance Code: Codes starting with an “H” signal maintenance is required. While the boiler continues to function, it needs professional attention.
• Cause Error: Three-digit codes displayed during a blocking or locking error help pinpoint the root cause.

Worcester Bosch Greenstar i System/Combi Boiler Error Codes

The Worcester Bosch Greenstar i series, one of the best-selling combi boilers, uses a variety of codes to alert homeowners to issues. Here’s a list of common error codes for this model:

• FD: Power interrupted.
• C7: Fan not running during start-up.
• C6: Fan speed too high or too low.
• C1: Fan stopping during operation.
• E2: Flow temperature issue.
• E9: Primary flow temperature exceeding 95°C.
• EA: No ionization detected after ignition.
• A7: Domestic hot water sensor defect.
• A1: Pump stuck or running dry.
• E9: Flue or high-limit thermostat activated.

Worcester Bosch Greenstar Si Compact Error Codes

The Greenstar Si Compact, designed for smaller homes, shares some similarities with the Greenstar i but has its own unique error codes:

• T1: Ignition test.
• 9U 233: Heat Control Module (HCM) error.
• C6 215: Fan running too fast.
• C7 214: Fan not running.
• E5 218: Flow temperature too high.
• EA 227: No flame detected or flame signal loss.
• F7 228: False flame or flame detected before burner start.
• A1 281: Pump stuck or running with air in the system.
• D4 271: Temperature difference between flow and safety sensor exceeds limit.

Worcester Bosch CDi Classic Regular Boiler Error Codes

Though discontinued, the Worcester Bosch CDi Classic remains popular in many homes. Here are some of its typical error codes:

• B1: Code plug not detected.
• C6: Fan speed too low or too high.
• E9: Safety temperature limiter in central heating flow tripped.
• EA: Flame not detected.
• F0: Internal error.
• FD: Reset button pressed by mistake—press again to resolve.

Worcester Bosch CDi Compact Error Codes

The CDi Compact is another reliable boiler with a compact design. Here are common error codes:

• T1: Ignition test.
• 9A 362: Incorrect HCM fitted.
• C6 215: Fan running too fast.
• E2 222: Flow sensor short circuit error.
• EA 227: No flame detected or flame signal loss during operation.
• FA 306: Flame detected after burner stop.
• A1 281: Pump stuck or running with air in the system.
• D4 271: Temperature difference between flow and safety sensor too high.

Worcester Bosch CDi Classic Combi Boiler Error Codes

The CDi Classic Combi Boiler was known for its power and performance. Here are its error codes:

• A1: Water leakage or pump issues.
• A7: Hot water sensor defect.
• C6: Fan speed too low or too high.
• EA: Flame not detected due to gas issues.
• F0: Gas valve/control box error.
• FA: Flame detected after gas shut off.

Worcester Bosch CDi Highflow Error Codes

The CDi Highflow is designed for homes with high hot water demands. Here are some of its error codes:

• A1: Pump running dry or air in the system.
• A7: Domestic hot water sensor defect.
• B7: Burner control error.
• D6: Internal heat bank overflow.
• EA: Flame not detected.
• E9: Safety temperature limiter tripped.
• FA: Flame detected after gas shut off.

Worcester Bosch 8000 Style Error Codes

The Worcester Bosch 8000 Style is a premium boiler with sleek aesthetics and advanced features. Below are its error codes:

• 201 O: Fan not running during start-up.
• 227 V: No flame signal after ignition.
• 228 V: Flame signal without flame present.
• 306 V: Flame signal after fuel supply closed.
• 815 W/B: Low loss header temperature sensor faulty.
• 1017 W: Water pressure too low—requires topping up.
• 1073 W: Short circuit in the flow temperature sensor.

Error Code Solutions: General Fixes and When to Call a Professional

Understanding what an error code means is the first step to fixing the problem. Here’s what you can do in response to the most common issues:

1. Fan-Related Errors (C1, C6, C7)

Fan errors typically occur when the fan isn’t operating correctly, either due to blockage, incorrect speed, or complete failure.

Solution: Ensure the boiler isn’t obstructed. If the issue persists, contact a Gas Safe Engineer to assess or replace the fan.

2. Ignition and Flame Detection Issues (EA, FA)

These errors usually occur when the boiler cannot detect a flame or if a flame is present when it shouldn’t be.

Solution: Check the gas supply and ensure the ignitor and electrodes are clean. If the issue continues, a Gas Safe Engineer will need to inspect the gas valve and ignition system.

3. Temperature and Flow Sensor Faults (E2, E9)

Temperature-related errors can indicate overheating or incorrect temperature readings from the sensors.

Solution: Ensure that your system is properly vented and that the boiler’s pressure is within the recommended range. For persistent issues, sensor replacement may be required by a professional.

4. Pump Stuck or Dry Running (A1, A7)

When the pump isn’t circulating water correctly, the boiler will lock out to prevent further damage.

Solution: Topping up the water pressure and bleeding the system may resolve the issue. If not, a Gas Safe Engineer will need to check or replace the pump.

When to Call a Gas Safe Engineer

Many boiler issues can be resolved by resetting the system or addressing minor faults like low pressure. However, some problems require professional help:

• Fan and PCB errors: These components are vital to the boiler’s operation, and their replacement often requires technical expertise.
• Gas valve or ignition problems: Any issue with the gas supply or ignition system should be handled by a professional to ensure safety.
• Temperature sensor and pump failures: If resetting or topping up doesn’t fix the issue, a Gas Safe Engineer will need to inspect and replace faulty parts.

Conclusion

Worcester Bosch boilers are reliable, but like any appliance, they can encounter issues over time. Error codes make troubleshooting more manageable, helping you understand what’s wrong and how to address it. Some minor issues can be resolved at home, but for more serious faults, it’s essential to contact a Gas Safe Engineer to ensure safe and effective repairs. Regular maintenance can also prevent many of these problems, ensuring your boiler runs efficiently for years to come.