Common problems guide

The most common Worcester Bosch Greenstar 8000+ Style problems

The faults most likely to send a Worcester Bosch Greenstar 8000+ Style into lockout — with plain-English causes, what to check first, estimated repair costs and whether you need a Gas Safe engineer.

99 documented codes
6 most common
6 DIY-safe checks
0 engineer needed

The 6 most common faults

01
204 High DIY-safe

Your boiler has sensed that the water temperature has risen above the level it was set to reach, leading it to shut down for safety.

What to try first

Check that all radiator valves are fully open to allow water to circulate.Ensure there is enough water pressure in the system by checking the digital gauge.Restart the boiler using the reset button on the touch screen.

Est. cost
£120-£350
Parts
Circulation Pump, Flow Temperature Sensor (NTC), Main Heat Exchanger (Cleaning)
Full guide for 204
02
227 High DIY-safe

Your boiler is failing to light the gas even though it is trying to, which prevents your heating and hot water from working.

What to try first

Check if other gas appliances (like a hob) are working to ensure gas is reaching the propertyCheck if your gas meter has credit (if using a pre-payment meter)Hold the 'Reset' button on the front of the boiler for 3 seconds

Est. cost
£120-350
Parts
Ignition Electrode, Flame Sensing Probe, Gas Valve
Full guide for 227
03
1017 High DIY-safe

Your boiler has stopped working because the water pressure inside the system has dropped below the minimum level required to operate safely.

What to try first

Locate the internal or external filling link (often blue levers or a braided hose under the boiler).Slowly open the valves until you hear water entering the system.Watch the digital display or pressure gauge until it reaches between 1.0 and 1.5 bar, then close the valves completely.

Est. cost
£0-120
Parts
Filling loop, Pressure sensor, Expansion vessel
Full guide for 1017
04
2923 High DIY-safe

Your boiler has detected an internal electrical communication error, which means it has stopped running to prevent damage to its electronic components.

What to try first

Press the 'Reset' button on the front display panel and hold for three seconds.Wait up to 10 minutes for the boiler to complete its restart sequence.Ensure your household electricity supply is stable and you have not recently had a power cut.

Est. cost
£280-550
Parts
Main Printed Circuit Board (PCB), Wiring Harness
Full guide for 2923
05
2925 High DIY-safe

Your boiler has experienced an internal electrical error that has caused it to stop working for safety.

What to try first

Press the 'Reset' button on the front control panel once.Wait up to 10 minutes to see if the boiler restarts normally.If the code persists or returns immediately, do not attempt further repairs and contact a Gas Safe engineer.

Est. cost
£250-550
Parts
Internal Wiring Harness, Printed Circuit Board (PCB)
Full guide for 2925
06
2950 High DIY-safe

Your boiler has tried to start up but cannot detect a flame, meaning it cannot provide heating or hot water.

What to try first

Check if other gas appliances (like a hob) are working to ensure gas is reaching the propertyCheck that your prepaid gas meter has creditTry resetting the boiler using the reset button on the touchscreen

Est. cost
£100-£350
Parts
Ignition Electrode, Flame Sensing Probe, Gas Valve
Full guide for 2950

on the Worcester Bosch Greenstar 8000+ Style

Circulation PumpFlow Temperature Sensor (NTC)Main Heat Exchanger (Cleaning)Ignition ElectrodeFlame Sensing ProbeGas Valve

Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.

Call a Gas Safe engineer if…

  • You can smell gas or see signs of a leak
  • The Worcester Bosch shows an Emergency or High severity code
  • The boiler keeps locking out after repeated resets
  • You've tried the DIY checks and the fault hasn't cleared
  • There's visible water leaking from the boiler
  • The flame is yellow or orange instead of blue

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See the full 99-code list for the Worcester Bosch Greenstar 8000+ Style