Worcester Boiler Blue Light Flashing: What Does it Mean?

Oscar Garner

By Oscar Garner

Last Updated on July, 2024

Are you panicking because your Worcester boiler is flashing a mysterious blue light? 

Don’t panic. You just have to understand what it’s trying to tell you. 

Worcester boilers have built-in error codes to signal you when there’s a fault. If you know what they are, it’s easy for you to solve the problem. 

In this article, I’ll take you through the fault codes accompanying the flashing blue light and explain its causes. That’s not all; I’ll tell you how to fix the error codes, too.

If you’re ready, let’s dive in! 

Quick Summary

  • Worcester boilers have built-in error codes and a flashing blue light to indicate faults and problems.
  • The most common causes of the blue flashing light include issues with gas supply, flue blockages, faulty flame sensors, and low gas or boiler pressure.
  • It is important to properly identify the cause of the error code and address it accordingly, either through DIY methods or by contacting a qualified gas-safe engineer.

Common Causes of Blue Flashing Light in a Worcester Boiler

pictures of a worcester boiler flashing blue light and fault code displayed

Your Worcester Bosch boiler will flash a blue light with an error code to alert you when there’s a fault in it. You must know the cause of the error code to be able to fix it properly. 

Below are some of the potential causes of the blue flashing light in your Worcester boiler:

  • Faulty gas supply.
  • Flue blockage.
  • Blocked condensate pipe.
  • Faulty flame sensor.
  • Problems with the ignition electrode.
  • Low gas pressure. 
  • Low boiler pressure.
  • Service mode. 

Worcester Boiler Flashing Blue Light Error Codes and How to Fix Them? 

As I mentioned earlier, if your Worcester boiler has a flashing blue light, it’s generally accompanied by an error code, making it easier to identify what’s wrong with your boiler. 

Knowing the causes of error codes’ causes will help you take necessary action to fix them before the damage increases. Let’s look at the most common error codes of the Worcester Bosch boiler, their causes, and methods to fix them in detail. 

Error Code EA 

The EA error code is the most common in Worcester boilers. It occurs when the flame is not detected. Causes of the EA error code include:

  • Gas supply problems.
  • Blockage in the flue.
  • Faulty flame sensor.
  • Issue with the ignition electrode. 

How do we identify the exact problem and fix it? Let’s discuss each one.

An Issue With the Gas Supply

If the boiler unit is not being supplied with gas or there’s a gas leak, it will show a flashing blue light. If you want to identify and confirm whether the issue is with the gas supply or the boiler, check your other home gas appliances, such as the oven or the hob. 

If they’re working fine, then the issue is with the boiler. If your other gas appliances are also not working, there’s an issue with the gas supply, like a gas leak or a faulty gas valve.

Gas leaks are explosive and dangerous. Hence, you must inspect your gas unit frequently as a precautionary measure. Even if you sense a slight gas leak, turn off your boiler, switch off the gas supply, and immediately contact a qualified gas-safe engineer. 

Flue Blockage

Worcester boilers produce hazardous gases while operating. Flues are special pipes fitted to eliminate these gases. Leaves, debris, and other waste materials can accumulate in flue pipes and block them. Vertical flues are more vulnerable to waste blockage.

When there’s a flue blockage, the hazardous gases accumulate and leak into your house. This is dangerous; therefore, your filter will show an error code with a blue flashing light immediately. If you suspect a flue blockage, turn off your Worcester boiler.

It’s better to turn off the gas supply, too. Then, contact a certified heating engineer immediately. Heating engineers will inspect and remove the clogs in the flue. If necessary, they might install a new flue.

You can install a flue guard to prevent debris from entering and blocking the flue in the future.

Problems With the Flame Sensor

Worcester boilers have a print circuit board (PCB) for functioning like all other boilers. If the print circuit board doesn’t sense a flame, it will shut off the gas supply to the boiler completely to prevent gas buildup. Then, the blue light will start to flash. 

Engineers will inspect if the flame sensor works properly and fix the issue. They are hard to fix. So, most of the time, flame sensors are replaced.

Faulty Ignition Electrode 

The ignition electrode sparks boiler gas once released into the combustion chamber. If there’s a failure in the ignition electrode, the boiler will stop working entirely with a flashing blue light. 

If the filter works continuously with a faulty ignition electrode, the boiler gas will accumulate in the combustion chamber and explode. So, the function of the filter is stopped to protect it from further damage. Gas engineers will inspect and replace the ignition electrode if it’s damaged.

Tip: There are many reasons for the EA code. Hence, we recommend contacting a gas-safe engineer if you see an error code EA accompanied by a blue light flashing rather than trying to solve it by yourself. 

Error Code CE207: Low Boiler Pressure

a picture of a worcester boiler flashing blue light

Boiler pressure is the pressure of the hot liquid inside your boiler. It must be at an optimum level for the heating system to function. If the pressure is not enough, the Worcester filter will display the CE207 error code with a flashing blue light. 

If this happens, first check the pressure gauge to confirm the pressure is low. Generally, a pressure of 1.5 bar is required for the boiler to function properly.

If the pressure falls below 1 bar, it’s too low. However, this pressure range can change according to the filter model. So, find out your filter’s ideal pressure gauge range from the manual. Boiler pressure reduces gradually with use. What should you do if the boiler pressure is low?

You must repressurise or top it up with water. The repressurising process varies with the filling system present in your boiler. 

It can be an external filling loop, a keyed internal filling loop, or a keyless internal filling loop. Identify the type of filling system you have and then go through the manual for instructions on topping it up. You can also watch some videos to do it more accurately. 

Don’t top the boiler too much. If it happens accidentally, bleed the radiators till you bring back the water pressure to the normal level. 

Repressurising is a simple process, and you don’t need an engineer to do it. However, get your filter inspected for any potential leaks from time to time.

Error Code D5 or EA: Condensate Pipe Blockage

Your boiler produces acidic water as a by-product of its operations. A condensate pipe releases the wastewater from the boiler into the drain. 

All condensing boilers manufactured after 2005 have condensate pipes. When they’re blocked, your Worcester boiler will display error code D5 or EA with a flashing blue light. 

During the winter season, wastewater freeze resulting in a frozen condensate pipe. You can solve this issue simply by pouring hot water to thaw the frozen water.

However, ensure the water is not boiling, as it can damage the pipes. Moreover, a large amount of wastewater will splash out after thawing the frozen condensate pipe.

Take precautions to avoid getting splashed by this water. If you’re uncomfortable doing this, contact a professional to do it for you. According to the Heating and Hotwater Industry Council regulations, all external condensate pipes must be internalised into a soil stack.

This helps to protect your condensate pipe from getting blocked up during the cold season. The condensate pipe can also get blocked due to debris deposits. You must contact a boiler engineer to internalise your condensate pipe or to flush out the debris.

Error Code C6: Faulty Fan 

a worcester boiler faulty fan error

The boiler fan removes toxic fumes into the environment through the flue, making it an important safety feature. Hence, whenever the fan stops working, your Worcester boiler blue light will flash, displaying the error code C6.

The boiler fan might not be working due to many reasons, such as:

  • Broken fan. 
  • A worn-out shaft or worn-out bearings in the fan. 
  • Faulty or loose wiring.
  • Issue with the printed circuit board. 

Additionally, issues with the flow or return temperature sensor can also trigger the error code C6 which is accompanied by the blue light. This happens due to a faulty temperature sensor or blockages in the system. 

If your Worcester boiler displays the error code C6, don’t try DIY methods to fix it. Instead, call a qualified gas-safe engineer. 

Gas-safe engineers will inspect your boiler and determine which component/components are causing the issue. Sometimes, they’ll be able to repair it. If not, the damaged component must be replaced. 

Error Code E9: Overheated Device

If your Worcester boiler displays the error code E9 with a flashing blue light, the gas boiler might be overheated. 

The Worcester Bosch boilers have a safe temperature range. Excess temperature can cause damage to the internal components of the boiler. Hence, its temperature sensor ensures the water flowing inside doesn’t exceed the safety limit. 

Overheating can occur due to many reasons, such as: 

  • Problems with the diverter valve.
  • Faulty wiring.
  • Blockages in the system.

There are no DIY methods to resolve the E9 fault code. Contact a heating engineer to fix this problem. 

Service Mode

If the blue light flashes in rapid succession without displaying an error code, it means your gas boiler has entered the service mode. 

If you serviced your gas boiler recently, the gas safe engineer might have left it in the service mode, or you or a family member might have accidentally knocked it to enter into service mode. 

You don’t have to worry about this at all. Reset your Worcester boiler and the issue will be fixed. Keep reading to find out how to reset your Worcester boiler.

Red and Green Lights Flashing in Worcester Boilers

If there’s a blue light flashing in your Worcester Bosch boiler, there’s a fault in it. You can guess the fault with the help of the error code displayed. However, you need to contact a gas-safe engineer to determine the problem. 

If your boiler flashes a red light, it needs servicing. Call a professional to get this done. The green light indicates your boiler is working correctly. So you have nothing to worry about. 

How Do I Reset My Worcester Boiler?

resetting a worcester boiler

If your Worcester boiler flashes a blue light 30 seconds after switching on, it indicates a fault in it. Specific fault codes can be resolved by resetting your boiler. Here’s how to do it. 

Find the reset button and hold it for 3 seconds. Worcester boilers come in different models and designs, such as Worcester Bosch boilers, combi boilers, Worcester Greenstar boilers, etc. 

Hence, the reset button will be in different locations. Use the manual to locate it. Some boilers don’t have a reset button. Instead, they have a reset light on the temperature dial.

If you have this type of model, turn the temperature dial until it reaches the reset setting, hold it for 3 seconds, and then return to its normal position. Worcester boiler error codes are displayed to protect your boiler from further damage. You can fix some of these error codes yourself. 

For example, if the boiler pressure is low, top it with water. If the boiler is in the service mode, reset it. Some error codes can be dangerous, such as a gas leak or overheating.

Therefore, we recommend that you get your boiler inspected by a gas-safe engineer rather than trying to fix it by yourself.

Gas-safe engineers would inspect your boiler carefully and find out the cause of the fault. Sometimes, repair or replacement would solve the issue. If there’s irreparable damage, you must consider a new boiler installation. 

Useful guides:

Did You Identify the Cause of Your Worcester Boiler’s Error Code?

A flashing blue light on your Worcester boiler indicates a fault. The fault could be due to a faulty gas supply, condensate pipe blockage, flue blockage, issues in the heating system, or lower boiler pressure.

First, try to identify the cause using the error code. If it’s something fixable, like low boiler pressure, fix it. 

If not, contact a gas-safe engineer. Some error codes have more than one cause. Hence, it’s better to call an engineer and inspect your boiler rather than try fixing it yourself.


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