BoilerFaultCodesIdeal Pb Fault Code
Also written as PB — same fault.
The Ideal Pb fault code means: your heat pump has temporarily paused its operation to prevent internal components from freezing during extremely cold weather.. It appears on 1 Ideal model in our database.
Technical description: Frost protection occurs; outdoor unit will stop operating.
What causes the Ideal Pb fault?
This code appears when the outside temperature drops low enough that the unit needs to protect its internal pipework and heat exchanger from freezing. It occurs because the system has detected a risk of ice buildup and has paused normal heating to circulate water or activate internal heaters. This is a built-in safety feature designed to prevent permanent damage to the outdoor unit during cold snaps.
This code is strictly seasonal and will only appear during the winter months when outdoor temperatures approach or fall below freezing.
DIY fix possible
Check that the outdoor unit is clear of snow, ice, or leaf debrisEnsure the airflow around the outdoor unit is not obstructedWait for the unit to complete its automatic defrost or warming cycle
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Gas Safe Register →Ideal models that show the Pb fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal Pb fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026