How to Reset a 'BLOCK' code

April 11 2025 , 7 min reading time

Seeing a ‘BLOCK’ error on your WES E-Compact, Trianco Greenflame, Bioflame, or Greenflame boiler? Learn what it means, how to read the code, and how to reset it safely.

Understanding 'BLOCK' Error Codes on WES E-Compact, Trianco Greenflame, Bioflame, and Greenflame Boilers

If your boiler is displaying ‘BLOCK’, it does not mean there is a physical blockage. Instead, it indicates that the boiler has entered an error state and has shut down as a safety measure.

To the right of the ‘BLOCK’ message, you will see an error code (e.g., Er12). This code is crucial in diagnosing the issue. Below is a comprehensive guide to these error codes, their meanings, and how to resolve them.

You should always speak with your manufacturer-approved service engineer before making any changes or remedying issues with your boiler. If in doubt, please call us on 01772 284 626

How to Read & Reset ‘BLOCK’ Errors

📌 First, identify the error code displayed next to ‘BLOCK’.
📌 Follow the steps below to troubleshoot and clear the issue.
📌 To reset an error, press and hold the power on/off button for three seconds unless otherwise stated.

Boiler Error Codes & Troubleshooting

Er01& Er04 – Water Safety Thermostat Activated

✅ Issue: Overheating detected by the safety thermostat.

Allow the boiler to cool down.
Press and hold button B for three seconds.
If the error persists, contact a manufacturer-approved engineer here

Er05 – Exhaust Over-Temperature

✅ Issue: The exhaust gases are too hot, which could indicate airflow issues.
🔧 Fix:

Ensure the baffle(s) is correctly positioned within the combustion chamber.
Clean the combustion chamber thoroughly.
Verify that the left-side temperature reading is accurate. If the sensor displays three dashes (---), it is faulty and should be replaced. Click here for the sensor
Ensure a manufacturer-approved engineer has serviced the boiler

Er09 – Low Water Pressure

✅ Issue: The system is detecting insufficient pressure.
🔧 Fix:

Check for leaks in pipes, radiators, or the pressure relief valve.
Re-pressurise the boiler if the pressure is below 1 bar.
If the issue persists, contact your service provider
🔗 Need a new pressure sensor?

Er10 – High Water Pressure

✅ Issue: The system pressure is too high.
🔧 Fix:

Contact your installer to release excess pressure safely.

Er12 – Failed Ignition

✅ Issue: The boiler failed to ignite properly.
🔧 Fix:

Empty any unburnt pellets from the burner pot.
Press and hold button B for three seconds to reset.
Replace your ignition element

Er13 – Accidental Extinguishing (Low Exhaust Temperature)

✅ Issue: The boiler flame went out due to low exhaust temperature.
🔧 Fix:

Empty any unburnt pellets from the burner pot.
Press and hold button B for three seconds.
If the issue persists, contact your service provider.

Er15 – Loss of Voltage (Power Cut)

✅ Issue: The boiler often detected a loss of power after a power cut.
🔧 Fix:

Empty any unburnt pellets from the burner pot.
Press and hold button B for three seconds.

Er18 – Lack of Pellets

✅ Issue: The pellet sensor detected a lack of fuel in the hopper.
🔧 Fix:

Refill the hopper with pellets.
Press and hold button B for three seconds.
If the issue persists, it may be due to a malfunctioning feed motor or sensor. Please contact us if you require additional assistance.

Er34 – Low Vacuum Pressure

✅ Issue: The system is detecting insufficient vacuum pressure.
🔧 Fix:

Ensure the boiler has been serviced by a manufacturer approved technician
Ensure all doors and ash pans have been put back correctly and have made a good seal on the boiler
Press and hold button B for three seconds to reset.
Contact your service provider if your issues continue

When to Call a Professional

🚨 If an error persists after troubleshooting, it may require expert diagnosis. Contact a professional engineer to inspect and repair your boiler.

🔧 Need Professional Help?
📞 Book a boiler engineer

Key Takeaways

✔️ ‘BLOCK’ does not mean a physical blockage, but an error state.
✔️ The error code next to ‘BLOCK’ tells you what’s wrong.
✔️ Check for fuel supply, pressure issues, and overheating causes before restarting.
✔️ Persistent errors may require new parts or professional servicing.

Need Spare Parts?

🛠 Order genuine boiler parts here:
👉 Buy spare parts now

🚀 Need an Expert Engineer?
🔧 Book a service with Tisigo