Navien Error Code E001

What Does E001 Mean?

Error code E001 indicates overheating of the heat exchanger in your Navien boiler. This is a safety mechanism to prevent damage to the boiler's internal components.

Common Causes

1. Restricted water flow through the heat exchanger
2. Scale buildup on the heat exchanger surfaces
3. Faulty temperature sensor providing incorrect readings
4. Pump failure preventing proper circulation
5. Blocked filters restricting flow

What You Can Do

Immediate Steps

1. Turn off the boiler and allow it to cool completely
2. Check radiator valves are fully open
3. Inspect the pressure gauge - ensure system pressure is between 1-1.5 bar
4. Check for visible leaks around the boiler and pipework

When to Call an Engineer

Contact a Gas Safe registered engineer if:

• The error persists after the boiler has cooled
• You notice unusual noises from the boiler
• System pressure drops rapidly
• You're unsure about any checks

Prevention

• Annual boiler servicing to prevent scale buildup
• Regular system pressure checks
• Ensure all radiator valves remain fully open during heating
• Consider a system flush if the boiler is over 5 years old

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Note: This fault may appear on NCB-CE, NCB300, NCB500, NCB700, and LCB700 models. On Smart Plus displays, it may show as "Error Display on Smart Plus - Error code on boiler."