E33 Low

ECA E33 Fault Code

The ECA E33 fault code means: your boiler is having trouble communicating with the sensor that monitors the temperature outside, which may cause your heating to run at the wrong temperature.. It appears on 4 ECA 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: Outdoor temperature sensor failure
Typical repair cost £90-160 (including labour)

DIY fix possible

Locate the external temperature sensor on your outside wall if you have one.Inspect the sensor and the visible wiring for any obvious signs of damage or loose connections.Press the Reset button on the boiler control panel to see if the fault clears.

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ECA models that show the E33 fault code

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

Source

ECA E33 fault code information on this page is sourced and cross-checked against the official ECA service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026