Blocking Error Medium

Potterton Blocking Error Fault Code

Also written as BLOCKINGERROR — same fault.

The Potterton Blocking Error fault code means: your boiler has temporarily paused its operation because it has detected a minor inconsistency in its internal readings, such as water pressure or temperature.. It appears on 2 Potterton models 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: Control Status: Blocking Error (Failure to carry out a step or malfunctioning component)

What causes the Potterton Blocking Error fault?

This fault occurs when the boiler's internal sensors detect a reading that is slightly outside of the normal operating range, leading the system to pause for safety. This is most commonly caused by a drop in system water pressure or a temperature sensor that is beginning to provide inconsistent data to the control board.

This issue is more frequent in autumn when the heating is turned on for the first time after summer, as stagnant water and settled debris can affect sensor accuracy.

Typical repair cost £0-120 (including labour)

DIY fix possible

Check the central heating pressure gauge is between 1.0 and 1.5 barTurn the power switch to the boiler off and back on again after 30 secondsCheck that all radiator valves are open and not blocked

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Potterton models that show the Blocking Error fault code

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

Source

Potterton Blocking Error 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