How to troubleshoot Navien boiler problems

Even though it’s a relative newcomer to the UK boiler market, Navien is one of the most trusted manufacturers there is. Across the Far East, consumers see Navien as the go-to brand for domestic home heating solutions, celebrating their industry-leading technologies, incredible energy efficiency and user-friendly features.

But no technology is perfect, and even the most reliable models can encounter issues from time to time. If you happen to experience a problem with your Navien boiler, getting it fixed promptly will be a top priority for everyone living in your property. Luckily, most issues can be rectified by a qualified professional pretty easily.

In this guide, we’ll walk you through some of the common problems you may encounter with a Navien boiler. We’ve split this into issues that you should be able to remedy yourself and urgent problems that should only be attempted by a Gas Safe registered engineer (such as the team at BOXT). 

Common Navien boiler problems and fixes

When there's a problem with your boiler, you'll usually notice an error code or an issue with your pressure gauge being too high or too low. 
Here are some of the most common Navien boiler problems and the steps you can take to fix them.

Please note: While these fixes can be performed yourself; if you don’t feel confident, don’t hesitate to enlist the help of a professional. 

Ignition failure

One of the most common error codes for Navien boilers is E003, which indicates there's an ignition fault.

If you encounter this error code, try restarting your boiler and checking the gas supply. If you've already tried those things and your boiler still fails to ignite, you should contact a Gas Safe registered engineer to determine the exact problem.

They'll likely need to access and inspect the boiler's controls to find the cause, whether it's debris or faulty parts.

Low pressure

If your pressure gauge is showing little to no pressure in your boiler, it likely means the water pressure in your boiler is too low for the system to work efficiently. You might also see the error code E302.

Low pressure can be down to numerous things, including a potential fault with the pressure relief valve or a leak within the boiler or on the system pipework.

If you aren't confident in attempting to raise your boiler's pressure yourself, please contact one of our expert Gas Safe registered engineers to help you.

High pressure

If your boiler's pressure gauge is too high, contact a Gas Safe registered engineer who will be able to give you expert advice.
For more information, see our complete guide to boiler pressure.

Urgent Navien boiler problems and fixes

Below are some of the most common urgent boiler problems and their potential causes. If you encounter one of these issues with your boiler, it is essential to seek an emergency boiler call out from a Gas Safe registered engineer. 

Important: Do NOT attempt these fixes yourself. 

Overheating heat exchanger

An overheating heat exchanger (error code E016 or E046) occurs when the component responsible for transferring heat from the burner to the water becomes excessively hot.

This can be caused by issues such as a lack of water flow or blocked pipes. An overheating heat exchanger can lead to serious safety hazards, including potential damage to the boiler and a risk of carbon monoxide leakage, which is also why it’s important to have a working carbon monoxide alarm.

If you suspect this problem, it is crucial to contact a Gas Safe registered engineer to diagnose and address the issue, ensuring both your safety and the efficiency of your boiler.

Flue issue

The boiler flue is a component that connects to your Navien boiler and safely transports the combustion gases to outside 
Factors like corrosion or obstructions in the flue/exhaust pipe can cause issues, potentially leading to harmful carbon monoxide leaks within your home.

If you encounter any flue related problems or suspect a malfunction, or blocked condensate, it's critical to contact a Gas Safe registered engineer without delay.

Temperature sensor issue

The temperature sensors (thermistors) in your Navien boiler are responsible for monitoring and regulating the water's temperature within the appliance.

Issues can include general wear and tear, electrical problems, or sensor misplacement, causing the sensor to give inaccurate readings.

You shouldn't try to fix any underlying issue yourself. Call a Gas Safe registered engineer, who will replace the sensor or find the cause of the inaccurate readings for you.

Choose BOXT Home Cover

We know how stressful it can be when your boiler stops working. That's why, at BOXT, we offer home cover plans with no call-out or excess charges as standard.

Our Gas Safe registered engineers are experienced in installing and maintaining Navien boilers too, so you, and your heating, will be in safe hands.

For more boiler advice, whether that’s information on what happens when a new boiler is fitted, how to clear an airlock, and everything you need to know about full boiler protection plans, check out our dedicated boiler guides.

If you're just after some guidance, you can message us on our Live Chat where you get the best advice from our heating specialists.