Worcester Bosch Boiler Error Codes

All 15 Worcester Bosch boiler codes

• EA / EA 227Burner didn't light (no flame detected)
• CE 207 / H07Heating system water pressure too low
• E9 / E9 224Overheat limiter tripped
• FdReset button pressed or power cut during a fault
• A1Pump has run dry
• C6Fan running too slowly
• E2Heating flow temperature sensor fault
• A7Hot water temperature sensor fault
• A8Lost contact with the controls
• F7Flame signal with the burner off
• FAFlame still present after the gas shut off
• F0Internal control fault
• b1Code plug not detected
• CCOutside weather sensor not reading
• SEAnnual service due

About Worcester Bosch boiler error codes

Worcester Bosch is a boiler maker based in Worcester, England, and part of the Bosch group. Its Greenstar and older CDi boilers are among the most common in UK homes. Older CDi models show a two-character code, while Greenstar boilers add a three-digit cause number, so note everything the display shows.

How to read Worcester Bosch boiler codes

Most codes on this page come from older Worcester Bosch boilers: the Greenstar CDi Classic ErP range and the HighFlow 440CDi and 550CDi ErP, which show a two-character code on its own (EA, E9, A1). Greenstar i and Si Compact models put a three-digit number under the letter code (Worcester's own example is EA with 227), so quote both when you book a repair. The newer Greenstar 2000 and 8000 ranges use numbered fault codes that aren't covered here, so check the manual for those.

How you reset depends on the model. On a Greenstar i a short press of Reset is enough. CDi models want the reset button held for about 3 seconds (5 seconds after thawing a condensate pipe). On the Greenstar 2000 and 8000 Life you press the two arrow or navigation keys together until the fault clears. Worcester notes that some codes can't be cleared by a reset. Everything behind the front casing is for a Gas Safe registered engineer, or a Registered Gas Installer (RGII) in Ireland.

Smell gas? Don't touch light switches, plugs or doorbells, and no flames. Turn the gas off at the meter if you can do it safely, open doors and windows, get everyone out and ring your gas emergency number once you're well away from the building. For an LPG boiler, use the supplier's number shown on the tank. A carbon monoxide alarm going off gets the same response.

Of the 15 codes on this page, 2 usually have a simple fix you can do yourself, and 11 usually need a technician. Each guide says which is which, so you don't pay for a service call you don't need, and you don't attempt a repair that isn't safe.

Boiler parts guide

All Worcester Bosch appliances

Before you start

• Write down the model name. It's printed on the front panel or on the data badge, and your operating manual names it too. Some code meanings depend on the range.
• Use the reset button. Your operating manual shows which button resets the boiler and how many times you may try. Don't keep pressing it if the same code returns.
• Look at the pressure gauge first. Vaillant, for one, asks for at least 1 bar with the heating cold and about 1.5 bar as the usual figure; your manual gives the number for your boiler.
• If you smell gas, open the windows, don't touch switches, turn the gas off at the meter if you can and call your gas emergency number from outside.