Tank Thermistor not in Tank Medium

Potterton Tank Thermistor not in Tank Fault Code

Also written as TANKTHERMISTORNOTINTANK — same fault.

The Potterton Tank Thermistor not in Tank fault code means: your boiler has lost the connection to the temperature sensor inside your hot water tank, meaning it cannot accurately tell when the water is hot enough.. It appears on 1 Potterton 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: Tank Thermistor not in Tank
Typical repair cost £120-220 (including labour)

Engineer required

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

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Potterton models that show the Tank Thermistor not in Tank fault code

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

Source

Potterton Tank Thermistor not in Tank fault code information on this page is sourced and cross-checked against the official Potterton service / installation manuals for each affected model.

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