E010 Error on Navien Water Heater? Comprehensive Fix Guide

The Navien Error Code E010 is specifically defined as an **Air Pressure Sensor (APS) Error**. This occurs when the unit’s main controller detects an abnormal signal from the air pressure sensor, indicating that the airflow required for safe combustion is either restricted, imbalanced, or the sensor itself has suffered an internal electrical failure.

If you are seeing this code, you are likely experiencing a sudden loss of hot water, potentially accompanied by the sound of the internal fan revving up and down as the system attempts to calibrate. You might also hear the igniter clicking repeatedly without the burner actually catching flame. While a “sensor error” sounds technical and daunting, it is a very common issue often caused by environmental factors or simple wear and tear. Rest assured, with a methodical approach to troubleshooting, this is a fixable problem that doesn’t necessarily mean you need a whole new unit.

Troubleshooting & Replacement Instructions

Follow these steps in order. We will move from the easiest, non-invasive checks to the more technical component replacements.

1. Safety First – Power and Gas: Before doing anything internal, turn off the power switch located on the bottom of the unit or unplug it from the wall. While not strictly necessary for an air error, it is best practice to shut off the gas supply valve to ensure no accidental discharge occurs while you are working near the combustion chamber.
2. External Vent Inspection: Go outside your home and locate the intake and exhaust pipes. Ensure there are no leaves, bird nests, or ice blocking the openings. Even a slight mesh screen clog from “dryer lint” or dust can trigger an E010. Clear any debris and try restarting the unit.
3. Access the Internal Components: Use your Phillips head screwdriver to remove the four screws securing the front cover of the Navien unit. Carefully pull the cover toward you and set it aside. Locate the Air Pressure Sensor—it is usually a small, circular or rectangular plastic component with two translucent silicone tubes and a wire harness attached to it, typically located near the top of the cabinet.
4. Inspect the Silicone Tubing: WARNING: Do not pull forcefully on the tubes or you may snap the plastic nipples on the sensor. Carefully disconnect the silicone tubes from the sensor. Inspect them for any water droplets or “gunk.” If you see moisture, blow through them to clear the blockage. Check the tubes for tiny cracks or pinholes; if air leaks out of the tube, the sensor will never get an accurate reading.
5. Test the Sensor Continuity: Set your multimeter to the Ohms (Ω) setting. With the wires disconnected from the sensor, place your probes on the sensor terminals. A healthy sensor should show a specific resistance or “Open/Closed” state depending on the model. If you have a manometer, you can apply a slight pressure to see if the switch clicks and the continuity changes. If the circuit stays “Open” regardless of pressure, the sensor is dead.
6. Replacing the Sensor (If Necessary): If the venting is clear and the tubes are perfect, but the code persists, the sensor must be replaced. Unplug the wire harness, unscrew the mounting bracket, and install the new Navien-certified APS. Ensure the tubes are reconnected to the correct ports (usually marked P1 and P2 or High/Low)—swapping these will result in a persistent error.
7. System Reset: Once reassembled, restore power and gas. Turn the unit on and run a hot water tap. The unit should initialize, the fan will purge the chamber, and the E010 code should vanish as the burner ignites.

What Triggers this Code?

What Triggers this Code? Detailed Diagnosis

Understanding the “Why” behind the E010 code is essential for a permanent fix. The Air Pressure Sensor is a safety gatekeeper; if it doesn’t “feel” the right amount of air movement, it kills the power to the burner to prevent carbon monoxide buildup or explosions.

• Obstructions in the Venting System: This is the most common culprit. Navien units use high-efficiency PVC or polypropylene venting. If a bird builds a nest in the terminal, if snow drifts block the intake, or if a bee’s nest is lodged in the pipe, the pressure differential changes. The sensor detects this resistance and triggers E010 to prevent incomplete combustion.
• Sensor Diaphragm Failure: Inside the APS is a tiny, sensitive silicone diaphragm. Over years of operation, the constant expansion and contraction can cause this diaphragm to stiffen, crack, or lose its elasticity. Once the physical component fails, the electrical signal sent to the PCB becomes erratic or non-existent.
• Moisture and Condensation: Because Navien heaters are condensing units, they produce moisture. If the venting is not pitched correctly back toward the unit, or if the internal “clear” silicone hoses that connect to the APS become clogged with condensation or debris, the sensor cannot “read” the air pressure accurately.
• Electrical Voltage Spikes or Loose Wiring: The APS communicates via low-voltage signals. A loose wire harness caused by unit vibrations or a minor power surge can damage the sensor’s internal circuitry, leading to a permanent E010 code even if the airflow is perfectly clear.

Common Symptoms of Error E010

Identifying the E010 code is usually straightforward because it will flash prominently on the front-mounted digital display or the remote controller. However, several physical symptoms typically precede or accompany this digital warning:

• Intermittent Hot Water: You may find that the water gets hot for a few seconds and then suddenly runs cold as the unit trips the error and shuts down the burner for safety.
• The “Fan Cycle” Loop: You might hear the combustion fan kick on at high speed, stay on for 30 seconds, and then shut off without the unit ever firing up. This is the system trying to clear the venting path and failing to verify the pressure.
• Audible Clicking: The igniter may click rapidly as the unit attempts to light the gas, but because the Air Pressure Sensor cannot confirm sufficient oxygen flow, the gas valve is never permitted to open.
• Complete Lockout: In many cases, after three failed ignition attempts related to air pressure, the unit will enter a hard lockout mode where it will not attempt to fire again until the power is cycled or the code is cleared.

How to Prevent Error E010

The E010 error is often a “maintenance” code masquerading as a “broken part” code. You can significantly reduce the chances of it returning by following these protocols:

• Annual Vent Screening: Once a year, especially before the winter heating season, check your exterior vent terminations. Installing a “bird screen” (specifically one approved by Navien to ensure it doesn’t restrict flow) can prevent debris from entering the high-velocity fan system.
• Maintain Proper Pitch: Ensure your vent pipes are pitched at least 1/4 inch per foot back toward the water heater. This allows condensation to flow into the unit’s internal condensate trap rather than pooling in the pipes, which is a leading cause of air pressure fluctuations.
• Install a Surge Protector: Since the APS and the PCB (motherboard) are sensitive to voltage fluctuations, plugging your Navien unit into a high-quality surge protector can prevent the electrical “frying” of the sensor’s delicate internal components during a lightning storm or power grid flicker.

Frequently Asked Questions

Q: Can I bypass the Air Pressure Sensor just to get a hot shower?
A: Absolutely not. The APS is a critical safety device. Bypassing it allows the unit to fire without verifying that exhaust gases are being safely vented. This can lead to Carbon Monoxide leaking into your home or a dangerous “roll-out” of flames from the burner. Always replace the part; never bypass it.

Q: I cleaned the vents and the code is still there. What now?
A: If the vents are clear, the issue is likely “static pressure” caused by an internal blockage. Check the heat exchanger fins (visible if you open the combustion chamber) for heavy soot or scale. If the air cannot pass through the heat exchanger easily, the APS will trigger Error E010. This may require a professional “descaling” or cleaning of the combustion side.

Q: Is Error E010 covered under Navien’s warranty?
A: Generally, yes. Navien typically offers a 5-year warranty on parts. However, the warranty usually only covers a defective sensor. It will not cover a service call where the technician simply has to remove a bird’s nest or clear snow from your vents, as those are considered environmental/maintenance issues rather than manufacturer defects.