How much does it cost to fix Ariston error code 40 ❍, yellow ❍?

Typical repair cost for the Ariston 40 ❍, yellow ❍ fault is £120-200 including labour.

40 ❍, yellow ❍ High

Ariston 40 ❍, yellow ❍ Fault Code

Q: What does the Ariston 40 ❍, yellow ❍ fault code mean?

Your boiler has lost the ability to measure the temperature of the water being sent to your radiators, so it has shut down to protect the system.

Also written as 40YELLOW — same fault.

The Ariston 40 ❍, yellow ❍ fault code means: your boiler has lost the ability to measure the temperature of the water being sent to your radiators, so it has shut down to protect the system.. It appears on 1 Ariston model in our database.

Technical description: C.H. Flow temp. probe circuit open / short circuit

Typical repair cost £120-200 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Ariston models that show the 40 ❍, yellow ❍ fault code

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

Clas One Repair: £120-200

Source

Ariston 40 ❍, yellow ❍ fault code information on this page is sourced and cross-checked against the official Ariston service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026