Updated: 12th June, 2025
In this guide, we are going to highlight the most common Worcester BOSCH errors that can show up on your boiler and explain what they mean so you can solve any issues yourself at home.
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A boiler error code is an alphanumeric indication displayed on your boiler's control panel. These codes are used by manufacturers to help identify specific issues or faults within the boiler system.
Each code corresponds to a particular problem, such as pressure loss, ignition failure, or overheating. By understanding these codes, homeowners can diagnose issues more efficiently and determine whether they can be resolved through simple troubleshooting or require professional attention.
Before you begin to stress and worry about being out of pocket when a code appears on your Worcester Bosch Greenstar boiler, there are two things you should consider first:
Worcester is renowned for having long warranties on their boilers, so the first thing to do whenever an issue arises is to check whether you are still covered.
In some cases, your boiler might be backed by a ten-year warranty which can make it cheaper to have any issues resolved by a professional.
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It is crucial to call a Gas Safe registered engineer if you encounter persistent or serious boiler issues indicated by error codes, such as frequent ignition failures, repeated pressure drops, or overheating.
Additionally, if you smell gas, see signs of carbon monoxide leaks, or if the boiler displays unfamiliar or complex error codes, professional intervention is necessary. Gas Safe engineers are certified to handle gas appliances safely and can ensure that your boiler is repaired correctly and efficiently, maintaining both your safety and the boiler's performance.
We have all heard the classic 'turn it off and on again' as a solution for when things go wrong, but there is some truth behind the cliché.
In some cases, an error code might show even if there is not a mechanical problem so to save yourself time and effort try turning the device off to see whether it goes away.
If the error code appears once the boiler has rebooted, it is time to look further into it.
Welcome to iHeat’s ultimate guide to understanding and troubleshooting Worcester Bosch boiler error codes. This user-friendly and SEO-optimised content will help you quickly diagnose and resolve boiler issues to keep your home warm and safe.
Meaning: Low water pressure.
Causes: Leak in the system, pressure relief valve issue, or recent bleeding of radiators.
Solutions: Repressurize the system to 1-1.5 bar. Inspect for visible leaks and repair them. Check the pressure relief valve for proper functioning.
Meaning: Fan speed too low.
Causes: Blocked flue, fan motor issue, or control board problem.
Solutions: Ensure the flue is clear of blockages. Check and replace the fan motor if necessary. Test the control board and replace it if needed.
Meaning: Overheat lockout.
Causes: Faulty pump, airlock in the system, or thermostat failure.
Solutions: Verify the pump operation and replace it if faulty. Bleed the system to remove any airlocks. Check the thermostat and replace it if necessary.
Meaning: Ignition failed.
Causes: Gas supply issue, ignition electrode fault, or flue gas sensor issue.
Solutions: Ensure the gas supply is turned on and the meter is functioning. Inspect and clean the ignition electrode. Verify the flue is not blocked.
Meaning: Sensor fault.
Causes: Faulty NTC thermistor, wiring issue, or control board fault.
Solutions: Check and replace the NTC thermistor. Inspect the wiring for any issues. Test and replace the control board if necessary.
Meaning: Hot water NTC sensor fault.
Causes: Faulty sensor, wiring issue, or connection problem.
Solutions: Replace the hot water NTC sensor. Inspect wiring and secure connections.
Meaning: Hot water outlet sensor short circuit.
Causes: Faulty sensor, wiring issue, or connection problem.
Solutions: Replace the hot water outlet sensor. Inspect wiring and secure connections.
Meaning: Coding card not recognised.
Causes: Incorrect coding card, card not inserted correctly, or faulty control board.
Solutions: Verify and replace the coding card if necessary. Ensure proper insertion. Test and replace the control board if needed.
Meaning: Burner control fault.
Causes: Burner issue, gas valve fault, or control board problem.
Solutions: Inspect the burner and clean or repair it. Check and replace the gas valve. Test and replace the control board if necessary.
Meaning: Safety temperature limiter.
Causes: Overheating, faulty safety temperature limiter, or circulation issue.
Solutions: Allow the boiler to cool down. Replace the safety temperature limiter. Ensure proper circulation by checking the pump and system pressure.
Meaning: No heating demand from external controls.
Causes: Faulty external controls or wiring issue.
Solutions: Inspect and repair external controls. Check wiring connections.
Meaning: Return sensor fault.
Causes: Faulty sensor or wiring issue.
Solutions: Replace the return sensor. Inspect wiring and secure connections.
Meaning: Flow sensor fault.
Causes: Faulty sensor or wiring issue.
Solutions: Replace the flow sensor. Inspect wiring and secure connections.
Meaning: Flow temperature sensor fault.
Causes: Faulty sensor or wiring issue.
Solutions: Replace the flow temperature sensor. Inspect wiring and secure connections.
Meaning: Water pressure sensor fault.
Causes: Faulty sensor or wiring issue.
Solutions: Replace the water pressure sensor. Inspect wiring and secure connections.
Meaning: Condensate pump fault.
Causes: Faulty condensate pump or blocked pipe.
Solutions: Check and replace the condensate pump if necessary. Clear any blockages in the pipe.
Boilers can be a daunting purchase for many people as they’re an appliance with a lot of responsibility, providing heat for you and your family is something you want to get right. Boilers aren’t exactly a quickly disposable item either, potentially lasting you a decade.
Effectively, new boiler cost can be split into two segments: the first is the actual boiler itself (unit price), and the second is the cost of the boiler being installed (set up) in your property by an expert engineer.
Here at iHeat, we want to remove all of this undue stress and make the decision making process of upgrading to a new central heating system, as easy as possible.
Boiler costs can vary depending on a number of factors including their brand, model, fuel, output, warranty, labour and installation type. Typically a new boiler will cost between £1,845 and £3,500, below is a list of average boiler installations offered by iHeat (guide only).
Installation Type | Price (inc VAT) | |
Combi to combi swap | £1,845 | |
System to combi conversion | £2,499 | |
New boiler install | £2,899 | |
Back boiler to a combi | £3,299 | |
System to system | £1,945 |
Worcester boilers use fault codes to help identify issues with the system. Common fault codes include:
Each code corresponds to a specific issue, and you can find the full list of codes in your boiler’s manual or on the Worcester Bosch website.
Common faults with Worcester combi boilers include:
These issues can often be resolved with regular maintenance, such as checking the pressure and clearing condensate pipes.
A flashing light on a Worcester boiler usually indicates a fault or error. The flashing pattern can point to specific issues like low pressure, ignition failure, or a blocked condensate pipe. Check your boiler's manual or the manufacturer's website for details on interpreting the flashing pattern.
To find the error code on your Worcester boiler, check the display screen or the indicator lights. Most models will show an alphanumeric error code when something is wrong. The user manual will explain what each code means and how to resolve it.
The error code for low pressure on a Worcester boiler is typically F22. This indicates that the water pressure is too low, and you’ll need to repressurise the system to bring the pressure back to the recommended level (usually around 1 to 1.5 bar).
A flashing light on a Worcester boiler typically means there is a fault or issue that needs attention. The exact meaning depends on the flashing pattern and the specific model of your boiler. It could indicate a range of problems, such as low pressure, ignition failure, or a blocked condensate pipe.
To reset the red flashing light on your Worcester boiler, turn off the power to the boiler for about 30 seconds, then turn it back on. If the red flashing light persists, check for any error codes displayed on the screen. If the issue remains unresolved, it’s best to call a professional to inspect the boiler.
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