What does the Worcester Bosch Group 1, 4 flashes fault code mean?

Your boiler is failing to light the burner, meaning it cannot produce heat or hot water.

How much does it cost to fix Worcester Bosch error code Group 1, 4 flashes?

Typical repair cost for the Worcester Bosch Group 1, 4 flashes fault is £150-300 including labour.

First safety timing error/ignition timing error. The flame was not established during the first four seconds of the ignition period.

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

Almost always a stuck diverter valve on combis.

Lockout fault with a reset-needed pattern.

Older boilers — thermocouple, draught, gas supply.