How much does it cost to fix Chaffoteaux error code 30-80 (M, M, L, L, M, M)?

Typical repair cost for the Chaffoteaux 30-80 (M, M, L, L, M, M) fault is £120-200 including labour.

30-80 (M, M, L, L, M, M) High

Chaffoteaux 30-80 (M, M, L, L, M, M) Fault Code

Q: What does the Chaffoteaux 30-80 (M, M, L, L, M, M) fault code mean?

Your boiler has detected that the water temperature sensor is not providing a valid reading, causing the system to stop working as a safety precaution.

Also written as 3080MMLLMM — same fault.

The Chaffoteaux 30-80 (M, M, L, L, M, M) fault code means: your boiler has detected that the water temperature sensor is not providing a valid reading, causing the system to stop working as a safety precaution.. It appears on 2 Chaffoteaux models in our database.

Technical description: Thermistor inlet heating bypassed

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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Chaffoteaux models that show the 30-80 (M, M, L, L, M, M) fault code

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

Source

Chaffoteaux 30-80 (M, M, L, L, M, M) fault code information on this page is sourced and cross-checked against the official Chaffoteaux service / installation manuals for each affected model.

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