High
604 on Worcester Bosch Greenstar 2000 GR2301iW 25 C

Your boiler has detected an internal communication error and has safely shut itself down to prevent it from operating incorrectly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

System fault burner control unit

From this model's manual
Verified against the Worcester Bosch/Worcester Bosch Greenstar 2000 Gr2301iw 2023 installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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All 143 fault codes on the Greenstar 2000 GR2301iW 25 C

Seeing a different code? Every code this model can display, in one place.

200201202203204208212214215224227228229229 B232 B233 V234 V235 V237 V238 V242 V244 V245 V246 –247 –249 V250 V251 V252 V253 V254 V256 V257257 –258258 V2592622632642652682692702732752812832843053063233283413423503513533543563573583603623633643658101010101310141018101910211023102510271037106810731074107510762051208529082909291029112912291329142915291629172918292029212922292329242925292629272928293029312932294029412942294329452946294729482949295029512952295329542954 B2955 B2956 O2957 V2958 V2959 B2960 B2961 V2962 V2963 B2964 B2965 B2966 B2967 B2971 B2972297329742981 V3071

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