203 Low

Worcester Bosch 203 Fault Code

The Worcester Bosch 203 fault code means: your boiler is currently in a temporary holding state and is waiting for a signal from your heating controls, such as your thermostat or programmer, to tell it to start.. It appears on 12 Worcester Bosch models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: System stand by

DIY fix possible

Check your external thermostat or boiler programmer to ensure they are set to 'on' or calling for heat.Turn the heating temperature dial on the boiler front panel up to ensure it is set higher than the current room temperature.Check if any smart heating app linked to your system has put the boiler into an 'off' or 'away' mode.

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like 203: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Worcester Bosch models that show the 203 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Worcester Bosch 203 fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026