Worcester Bosch 9/14 - 19/24 CBi Fault codes & diagnostics

6 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

Combi Natural Gas 14-24 2001-2005 Discontinued
Choose your boiler type

The 9/14 - 19/24 CBi range comes in 3 types

Pick the one you have. The fault codes, GC numbers and manual differ by type.

9/14 CBi RSF 6 codes · 2 GC numbers 14/19 CBi RSF 6 codes · 2 GC numbers 19/24 CBi RSF 6 codes · 2 GC numbers
Each model has its own manual A family spans several manuals, one per model or generation. Pick your model above and its page has the manual its fault codes were read from.

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
6 High
Just want the most common Worcester Bosch 9/14 - 19/24 CBi faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 6 documented codes

Tap any card for details

A

Your boiler has lost all power and is completely unresponsive, meaning it is currently unable to provide heating or hot water.

High Engineer only £120-250 Shared across the 9/14 - 19/24 CBi range

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Internal Fuse
  • Power Cable
Full explanation for A
B

Your boiler is receiving a signal to turn on but is failing to start the ignition process, suggesting a communication or sensor delay.

High Engineer only £120-250 Shared across the 9/14 - 19/24 CBi range

Parts commonly replaced

  • Printed Circuit Board
  • Flow switch
  • Ignition lead

Related codes

Full explanation for B
C

Your boiler is failing to ignite or stay lit, meaning it cannot produce heat or hot water because the flame is not being detected.

High Engineer only £120-250 Shared across the 9/14 - 19/24 CBi range

Parts commonly replaced

  • Ignition electrode
  • Flame rectification probe
  • Gas valve

Related codes

Full explanation for C
D

Your boiler has stopped working for safety reasons and is locked out, meaning it needs a manual reset or a professional technician to investigate the internal fault.

High Engineer only £120-250 Shared across the 9/14 - 19/24 CBi range

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB

Related codes

Full explanation for D
E

Your boiler has stopped working for safety reasons and is waiting for you to manually reset it to try and clear the fault.

High Engineer only £120-250 Shared across the 9/14 - 19/24 CBi range

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

Full explanation for E
F

Your boiler has detected an unspecified internal problem and has shut down as a safety precaution.

High Engineer only Shared across the 9/14 - 19/24 CBi range

Parts commonly replaced

  • Main control board
  • Wiring harness
  • Internal sensors

Related codes

Full explanation for F