Common problems guide

The most common Worcester Bosch Greenstar problems

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

The 6 most common faults

01

N/A Engineer

IF THIS IS NOT DONE THE APPLIANCE WILL INDICATE ERROR AND WILL NOT FUNCTION.

Full guide for N/A

02

Slow flash (normally off, flashes on) Engineer

Ignition lockout

Full guide for Slow flash (normally off, flashes on)

03

Slow flash (normally on, flashes off) Engineer

Flue overheat

Full guide for Slow flash (normally on, flashes off)

04

Fast flash Engineer

Volatile lockout (sensor, fan or code plug)

Full guide for Fast flash

05

2 pulses Engineer

Service mode switch in min position

Full guide for 2 pulses

06

5 pulses Engineer

Service mode switch in max position

Full guide for 5 pulses

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 6-code list for the Worcester Bosch Greenstar