Worcester Bosch CDi Classic Regular Boiler Error Codes Leave a Comment / Boiler Fault Codes, Worcester Bosch Boilers / By Emergency Plumbers / May 3, 2015 May 3, 2020 / Boiler Error Codes, Boiler Fault Codes, Combi Boiler, Domestic Gas Boiler, Worcester Bosch, Worcester Bosch CDi Classic Regular Boiler Worcester Bosch CDi Classic Regular Boiler Error Codes Fault Description System Behaviour B1 Code plug not detected C6 Fan speed too low E2 Central heating (CH) flow negative thermistor coefficient (NTC) sensor defective E9 Safety temperature limiter in central heating (CH) flow has tripped EA Flame not detected F0 Internal error F7 Flame detected even though appliance switched off FA Flame detected after gas shut off FD Reset button pressed by mistake