What does the Navien 300 fault code mean?

Your boiler has detected that a critical internal part is not warming up as expected, so it has shut down to protect itself from damage.

How much does it cost to fix Navien error code 300?

Typical repair cost for the Navien 300 fault is £150-300 including labour.

Navien 300 Fault Code: What It Means & How to Fix It

What the manual says

Manufacturer manual

300:Eng head undert SW: Engine head control temperature less than TempHeadGridDisconnect degrees C when CX relay is energised. The default value of TempHeadGridDisconnect is 150°C.

Shared across the range

This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Boiler cover options

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Related fault codes

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Your boiler has detected that a critical internal part is not warming up as expected, so it has shut down to protect itself from damage.

What the manual says

Engineer required

Avoid the next call-out bill

Related fault codes

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