E33 Medium

Chaffoteaux E33 Fault Code

The Chaffoteaux E33 fault code means: your boiler has detected that the external temperature sensor for your underfloor heating system is not sending a signal, which is preventing the boiler from firing.. It appears on 1 Chaffoteaux model in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: Floor heating thermostat open circuit (if fitted)
Typical repair cost £120-250 (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 E33 fault code

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

Source

Chaffoteaux E33 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 7 July 2026