Medium Lockout
E50 on Potterton Promax System HE Plus

Your boiler's temperature sensor for hot water has developed a fault, meaning the system may struggle to heat your water to the correct temperature.

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

Faulty components (referenced in fault finding section)

What causes this fault?

This fault occurs when the sensor responsible for monitoring the temperature of your hot water fails to send a reliable signal back to the main control board. The most common reason is that the internal component of the sensor has degraded over time or developed an electrical short, preventing it from reading the water temperature accurately. In some cases, it can also be triggered by a loose or damaged connection in the wiring leading to the sensor.

Engineer required

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

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