Navien Water Heater E515 - What It Means And How To Fix It Safely

That feeling hits you in the gut. You step into the shower expecting a rush of hot water, but all you get is a steady, disappointing stream of cold. You head to your Navien tankless water heater, and there it is—a cryptic error code blinking on the display: E515. It’s frustrating, confusing, and immediately makes you worry about a big repair bill.

I get it. As an HVACR technician, I’ve seen that look of concern on countless homeowners’ faces. But here’s the good news: you’ve come to the right place. I promise this guide will demystify the navien water heater e515 error, walk you through some safe and simple checks you can perform yourself, and help you understand exactly when it’s time to call in a professional.

In this complete navien water heater e515 guide, we’ll break down what the code means, explore its most common causes, and provide a step-by-step troubleshooting plan. You’ll gain the confidence to tackle the simple fixes and the wisdom to know when to ask for help, getting that glorious hot water flowing again.

What Exactly is the Navien Water Heater E515 Error Code?

First things first, let’s translate that code. An E515 error on your Navien tankless water heater points directly to a problem with the air pressure sensor or the venting system it monitors. Think of this sensor as a vigilant safety guard for your heater.

Its one and only job is to ensure that your unit’s exhaust and intake vents are completely clear before allowing the burner to ignite. If it detects any blockage, abnormal pressure, or airflow restriction, it immediately shuts the system down and displays the E515 code. This is not a malfunction of the code system; it’s a critical safety feature in action.

This “lockout” prevents potentially dangerous situations, such as the buildup of carbon monoxide gas if the exhaust vent is blocked. So, while it’s an inconvenience, you can be thankful your Navien is looking out for your safety.

Uncovering the Common Problems with Navien Water Heater E515

So, what’s causing this vigilant safety guard to sound the alarm? The E515 error is almost always tied to an issue with air moving in and out of the unit. Here are the most frequent culprits we see in the field, which are a great starting point for our common problems with navien water heater e515 checklist.

Venting and Intake Obstructions

This is, by far, the number one cause. Your high-efficiency Navien unit needs to breathe freely. Anything that gets in the way of its air intake or exhaust vent pipe can trigger the error.

Outdoor Debris: Snow, ice, leaves, and dirt are common offenders, especially after a storm or during seasonal changes.
Animal Intruders: Birds, wasps, and rodents sometimes find vent terminations to be the perfect spot for a nest.
Improper Installation: Vent pipes that are too long, have too many bends, or are sloped incorrectly can cause issues with both airflow and condensation drainage, leading to a blockage.
Condensate Issues: If the internal condensate trap is clogged or the drain line is blocked, water can back up and affect pressure readings.

Issues with the Air Pressure Sensor Itself

Sometimes, the problem lies with the monitoring system rather than an actual blockage. This is where a little more technical know-how is needed.

Damaged Tubing: The sensor is connected to the fan assembly by small rubber or silicone tubes. Over time, these can become cracked, brittle, or disconnected, causing a false reading.
Moisture in the Lines: Condensation can sometimes find its way into these small tubes, which interferes with the delicate pressure readings.
A Failed Sensor: Like any electronic component, the air pressure sensor can simply fail. It might get stuck “open” or “closed,” sending an incorrect signal to the main control board.

Internal Component Failures

While less common, the error can sometimes point to a more significant internal issue that prevents the unit from creating the correct amount of airflow.

Failing Fan Motor: The combustion fan (or inducer motor) is responsible for pulling in fresh air and pushing out exhaust. If this motor is failing or obstructed, it won’t spin at the correct speed to satisfy the pressure sensor.
Control Board Problems: In rare cases, the main control board (the “brain” of the unit) may not be correctly reading the signals from the air pressure sensor, leading to a false E515 error.

Your Step-by-Step Navien Water Heater E515 Guide for Safe DIY Checks

Alright, let’s roll up our sleeves and walk through a few safe checks together. Before you even think about picking up a tool, remember this: your safety is the top priority. We are only going to perform visual inspections. If at any point you feel unsure or uncomfortable, stop immediately and call a qualified technician.

Step 1: The Essential Power Cycle (The “Reboot”)

Sometimes, electronics just need a quick reset. A momentary power surge or a sensor glitch can occasionally trigger an error code that isn’t a “hard” fault. It’s the oldest trick in the IT book for a reason!

Unplug your Navien water heater from the wall outlet.
Wait for at least one full minute. This allows the internal capacitors to fully discharge and the control board to reset.
Plug the unit back in.

Listen as it powers on. If the error clears and the unit begins to operate normally, you may have just had a temporary glitch. However, keep a close eye on it. If the E515 error returns, it’s a sign of a real underlying issue that needs to be addressed.

Step 2: Visually Inspect Your Vent Terminations

Now, let’s go check on your heater’s “lungs.” Go outside to where the two white PVC pipes (one for intake, one for exhaust) exit your home. This is the most common trouble spot.

Look for Blockages: Carefully inspect the openings of both pipes. Do you see a bird’s nest, a pile of leaves, a snowdrift, or an ice dam covering the openings?
Check the Screens: Many installations have protective screens over the terminations. Make sure these are free of lint, cobwebs, or other debris.
Clear with Care: If you find a blockage that is easily and safely accessible, gently clear it away. Do not poke anything deep into the pipes, as you could damage internal components.

Safety Warning: Never climb a ladder or get on your roof to check vents unless you are properly trained and equipped to do so safely. If the vents are out of easy reach, this is a job for a professional.

Step 3: A Cautious Look Inside (Optional)

If you are comfortable doing so, you can take off the front cover of the unit for a quick visual inspection. Your owner’s manual will show you how to do this correctly.

Turn off the power to the unit before removing the cover.

Check the Condensate Trap: Locate the clear plastic condensate trap. Is it full of water or gunk? A clogged trap can cause pressure issues.
Inspect the Sensor Hoses: Find the air pressure sensor (it’s a small square component with two thin rubber hoses attached). Are the hoses pushed on securely at both ends? Do they look cracked, kinked, or damaged? Gently wiggle them to ensure they are snug.

If you see anything amiss here, like a disconnected hose, you may have found your culprit. If everything looks fine, it’s time to put the cover back on and move to the next step.

When to Put Down the Tools and Call a Navien Professional

You’ve done the basic checks, and the E515 error is still there. This is the point where DIY ends and professional service begins. Continuing to troubleshoot without the right tools and training can be dangerous and may cause more damage to your unit. Here is how to know it’s time to call for help.

The error code returns immediately after a reset and you can’t see any obvious external blockages.
You suspect the blockage is deep inside the vent piping.
You are not comfortable or able to safely access your vent terminations.
You noticed a cracked hose, a full condensate trap, or anything else inside the unit that you aren’t sure how to fix.
You hear unusual noises from the fan motor when the unit tries to start.

A certified Navien technician has specialized tools, like a manometer, to accurately measure air pressures and diagnose whether the problem is the sensor, the fan, the venting, or the control board. They can do it safely and efficiently, giving you peace of mind.

Navien Water Heater E515 Best Practices for Prevention

The best way to deal with an E515 error is to never see it in the first place. Following a simple navien water heater e515 care guide can save you from future cold showers and service calls. The benefits of navien water heater e515 prevention are clear: reliability, longevity, and efficiency.

The Power of Annual Maintenance

This is the single most important tip I can give you. Have a qualified technician perform a full maintenance service on your Navien unit once a year. During this service, they will:

Clean and inspect the burners and heat exchanger.
Flush the system to remove mineral scale.
Thoroughly inspect the entire vent system for integrity and blockages.
Test all sensors and safety controls, including the air pressure sensor.

Keep Your Vents Clear Year-Round

Make it a habit to glance at your vent terminations a few times a year. Check them after a big snowstorm, after the leaves fall, and in the spring when birds are nesting. Keeping the area around the vents clear of overgrown shrubs and bushes is also a great preventative step.

Understanding Sustainable and Eco-Friendly Navien Water Heater E515 Prevention

Thinking about a sustainable navien water heater e515 approach means thinking about efficiency. When your unit can breathe properly, it doesn’t have to work as hard. It burns fuel more cleanly and efficiently, which lowers your energy bills and reduces your carbon footprint. Proactive maintenance is not just good for your wallet; it’s an eco-friendly navien water heater e515 strategy that ensures your high-efficiency appliance is always running at its peak.

Frequently Asked Questions About the Navien E515 Error

Can I just keep resetting my Navien water heater if I get the E515 error?

No, this is not recommended. While a single reset can clear a temporary glitch, repeatedly resetting the unit ignores the root cause. The E515 code is a safety alert. Constantly overriding it without fixing the underlying airflow problem can put stress on components and potentially lead to an unsafe operating condition.

How much does it cost to fix a Navien E515 error?

The cost can vary dramatically. If it’s a simple blockage you clear yourself from the outside vent, the cost is zero. A service call for a technician to clear a vent or re-secure a hose might cost between $150 and $300. If a part has failed, like the air pressure sensor or the fan motor, you could be looking at a repair cost of $300 to $700+, depending on parts and labor in your area.

Is the Navien E515 error dangerous?

The error code itself is a safety feature that is preventing a dangerous situation. The underlying cause, however, can be dangerous. A blocked exhaust vent can cause harmful carbon monoxide (CO) to build up in your home. This is why you must never ignore this error and should address it promptly.

Facing an error code on a major appliance is never fun, but you’ve taken the first and most important step: seeking out knowledge. By understanding what the navien water heater e515 code means and knowing how to perform a few simple, safe checks, you are in a much better position to resolve the issue quickly.

Remember to prioritize safety, perform the basic visual inspections we discussed, and don’t ever hesitate to call a trusted professional when you’re out of your depth. A well-maintained Navien heater is a wonderfully efficient and reliable source of endless hot water.

Stay safe, and stay comfortable!

Author
Recent Posts

David Clark

Founder & Lead HVAC Specialist at HVACRLY

David Clark is the founder of HVACrly and a certified HVAC specialist with 10+ years working on residential and light-commercial systems. He turns complex heating, cooling, ventilation, and refrigeration topics into clear, actionable guides focused on safety and energy efficiency. When he’s not on a service call, he’s testing tools and writing step-by-step tutorials.