How to Reset Your Navien Water Heater Safely

Press the Front Panel Button to Clear Everyday Faults

When your Navien tankless water heater stops delivering hot water, the front control panel usually displays an error code (a warning number on the screen). Before you push any buttons, grab your phone or a notepad and write down that exact code. If the problem returns later, that number tells a repair technician exactly what went wrong inside the machine.

Most standard system alerts resolve with a simple push of a button. Navien control panels vary depending on the age of your unit, but resetting them requires only a moment once you locate the right control.

1. Locate the Reset button on your panel: On traditional models, look for a small round button clearly labeled Reset right below or beside the digital display. On newer touch-screen models, look for a Back arrow button or a dedicated touch point labeled Reset.
2. Press the Reset button once firmly: Hold the button down for roughly two seconds, then release it. Avoid mashing the button repeatedly, because rapid pressing can confuse the electronic control board.
3. Watch the screen reboot: The flashing error code should disappear. The screen will blink, and you should hear the internal fan begin a quiet spin cycle as the unit purges the combustion chamber with fresh air.
4. Run a hot water faucet: Walk to the nearest sink and open the hot water tap completely. Let the water run for 30 seconds to draw water through the unit.
5. Check the display screen: Look for a small flame icon or an active water flow icon to illuminate on the screen. If you feel warm water at the tap and the display shows the set temperature without flashing numbers, your reset worked.

If your model features a smooth glass touch interface without a visible reset icon, press the Power button once to turn the unit off. Wait five seconds, then press the Power button again to restart the system. This action clears minor transient glitches caused by brief drops in water pressure or slight electrical flickers.

Cut the Power Completely When the Screen Freezes

Sometimes the front control panel locks up completely. The screen might stay stuck on an error number, the touch panel might refuse to respond to your finger, or the display might show garbled digital symbols. In these situations, a button press will not work. You need to perform a complete power cycle (turning power completely off and back on).

Tankless water heaters rely on a small computer board to monitor gas valves, water sensors, and air blowers. Just like a home internet router, that computer board sometimes needs a full electrical drain to clear its working memory and boot up cleanly.

1. Locate the electrical connection: Most Navien water heaters plug directly into a standard 120-volt wall outlet located right next to the unit. If your unit is hardwired directly into a metal conduit without a wall plug, locate the electrical shutoff switch nearby or find the dedicated water heater switch in your home circuit breaker panel.
2. Disconnect the power: Pull the electrical plug firmly straight out of the wall outlet. If your unit is hardwired, flip the circuit breaker switch or the wall switch completely to the Off position.
3. Wait at least 60 full seconds: Do not plug the unit back in right away. The computer circuit board contains small capacitors (tiny parts that store electric charge to prevent sudden power loss). Waiting a full minute allows those internal parts to drain their stored electricity completely, which forces the internal memory to wipe clean.
4. Restore the electrical supply: Push the power plug firmly back into the wall outlet, or flip your circuit breaker back to the On position. You should hear a short beep, and the display panel should light up.
5. Power the system back on: If the panel remains blank after restoring power, press the front Power button once. The unit will run an automatic self-check routine that lasts about 15 seconds.
6. Verify hot water production: Open a hot water faucet in your kitchen or bathroom. Listen near the water heater for the steady click of the igniter followed by the soft roar of the gas burner starting up.

A full electrical power cycle settles temporary computer lockouts that a simple panel button cannot reach. If the error returns immediately after the screen lights up, the problem is not a computer glitch. An active mechanical or fuel issue is preventing the system from operating safely.

Inspect These Four Hidden Culprits Before You Reset Again

If your water heater clears its screen but trips back into a lockout (an automatic safety shutoff) the moment you call for hot water, do not keep resetting it. The machine is shutting down on purpose to protect your home. Before you assume a major part has failed, check these four common external issues that trigger false alarms.

• The gas supply valve is partially closed: Look directly underneath the water heater along the yellow or black iron gas pipe. You will see a manual gas shutoff valve, usually with a bright yellow or red handle. If that handle is turned across the pipe at an angle, gas flow is restricted. The handle must point straight in line with the pipe to deliver full fuel pressure. If a utility worker, plumber, or family member bumped the handle, the heater will spark, fail to light, and lock out with an ignition error code.
• The exterior exhaust or intake pipes are blocked: Tankless units breathe air from outside your house through two plastic vent pipes that exit through your roof or exterior sidewall. The intake vent (the pipe bringing outside air into the heater) can pull in dry autumn leaves, bird nests, or insects. In freezing winter weather, drifting snow or heavy icicles can choke these vent pipes completely. Go outside, find the two white PVC or polypropylene pipe hoods, and verify that both openings are completely clear of debris.
• The condensate drain line is frozen or clogged: High-efficiency condensing water heaters squeeze extra heat out of exhaust gases, which creates acidic runoff water during normal operation. A small clear or white plastic hose routes this liquid down to a floor drain or into a small neutralization box. If that drain hose pinches, clogs with dirt, or freezes solid during freezing winter weather, water backs up into the heat exchanger (the internal metal chamber that warms the water). An internal float switch detects the rising water and locks out the burner instantly. Homeowners who keep water heaters in cold outbuildings often run an electric heater for garage with thermostat to stop utility lines and drain hoses from freezing during severe weather.
• The cold water inlet filter screen is full of debris: Underneath the unit, right where the cold water pipe enters the bottom of the cabinet, sits a small threaded plug housing a cold water filter. This tiny mesh cylinder catches sand, mineral scale, and pipe grit before water enters the heating chamber. If that mesh fills with debris, water cannot move fast enough to trigger the internal water flow sensor. Turn off the cold water shutoff valve, place a small bucket beneath the unit, unscrew the filter plug, and rinse the plastic mesh under clean tap water before screwing it back in place.

Clearing an external blockage or opening a bumped valve often solves the problem immediately. Once you correct the underlying issue, perform one standard panel reset to clear the stored fault, and the water heater should fire up normally.

Never Force a Safety Reset on a Repeating Lockout

Pushing the reset button over and over without fixing the root cause is the most common mistake homeowners make. It can feel tempting to stand in front of the cabinet and press Reset every time the shower goes cold, but doing that creates real safety hazards and risks expensive equipment damage.

Every time an ignition failure code appears, the water heater has opened its internal gas valves and tried to strike a flame several times. If the burner fails to catch, a small cloud of unburned gas can linger inside the combustion chamber. When you force five or ten resets in rapid succession, raw gas accumulates inside the sealed chamber. When the igniter finally catches a spark, that trapped gas can ignite all at once with a loud bang, known as a delayed ignition. That sudden pressure spike can crack internal seals, warp the burner assembly, or damage the plastic venting pipes that route toxic exhaust out of your home.

Repeatedly forcing resets also causes severe thermal stress across the heat exchanger. If your unit is shutting down because of low water flow or overheating, forcing it to fire up again exposes internal metal components to extreme heat spikes without adequate water moving through to cool them down. Over time, that thermal shock causes hairline cracks in the metal, leading to internal water leaks that destroy the electronics below.

Treat an error code as an informative warning rather than an inconvenience. The system locks you out because one of its internal safety sensors detected abnormal temperatures, improper air pressure, or an unreliable flame. Follow the rule of two: try one button reset, and if that fails, perform one full 60-second power cycle. If the exact same code appears a third time, step away from the controls and look deeper into the cause.

Step Away and Call a Licensed Technician in These Moments

While clearing a simple electronic hiccup or cleaning an air vent is safe for any homeowner, certain water heater conditions demand professional training and specialized tools. Navien units handle high-voltage electricity, high-pressure water, and combustible fuel simultaneously. Knowing when to stop protects your household from fire, carbon monoxide exposure, and severe water damage.

If you encounter any of the following warning signs, stop attempting resets immediately, turn off the water heater, and call a qualified professional:

• You smell gas or sulfur: If you detect the unmistakable scent of rotten eggs anywhere near the water heater, do not touch the reset button, do not unplug the electrical cord, and do not flip any light switches. Any tiny electrical spark can ignite airborne gas. Evacuate everyone from the house immediately, leave the door open behind you, and call your local gas utility or emergency services from a safe distance outside.
• Water is actively dripping from inside the cabinet: If you see water pooling on the floor beneath the unit, or if water is dripping out of the metal casing seams, do not reset the unit. Water spraying inside the cabinet can short out the main computer board, rust the blower motor, or cause electrical shocks. Shut off the cold water isolation valve beneath the unit and call an authorized technician to locate the leak.
• The error code points to an internal electrical or sensor failure: Codes that indicate a faulty high-limit switch, a failed thermistor (a temperature sensor that tells the computer how hot the water is), a broken gas control valve, or an internal circuit board fault cannot be resolved from the front panel. These parts require diagnostic electrical testing with a meter and physical component replacement.
• You hear loud banging, screeching, or whistling sounds: A healthy tankless heater produces a gentle whirring fan sound and a steady, muted combustion hum. Loud metallic rattling, whistling like a tea kettle, or aggressive pounding sounds point to severe mineral scale buildup inside the heat exchanger, a failing combustion fan, or improper air-to-fuel ratios that require a deep chemical flush and combustion analysis.
• Visible soot, scorch marks, or melted plastic: Look at the white exhaust pipe where it connects to the top of the cabinet. If you see brown heat discoloration, black soot deposits, or warped plastic fittings, exhaust heat is leaking into the room. Shut off the unit at the circuit breaker immediately and leave it off until a certified gas technician inspects the vent run.

A licensed technician carries the pressure gauges, combustion analyzers, and factory diagnostic tools necessary to verify fuel pressure and check electrical resistance safely. Calling for help when a code refuses to clear saves you hours of frustration and keeps your home heating system safe for years to come.

FAQs

Where is the reset button on older Navien models compared to newer ones?

Older units typically feature a front panel with physical rubber or plastic push buttons. On those units, the Reset button sits directly below the digital display window, clearly stamped with the word Reset. Newer models use a smooth digital touch faceplate where the reset function is usually performed by tapping the Back button, or by touching the Power icon once to turn the screen off and back on.

Will resetting my water heater erase my custom temperature settings?

No, performing a panel reset or a complete power cycle will not erase your target water temperature. Navien water heaters store your preferred temperature settings and operational configurations on non-volatile memory chips inside the control board. When power returns or the error code clears, the heater will automatically reload your previously selected temperature setting.

Can a power outage cause my Navien water heater to lock out?

Yes, electrical grid flickers and sudden blackouts frequently trigger false error codes. When the power cuts out abruptly while the burner is firing, the exhaust fan stops immediately, trapping hot exhaust air inside the unit. That momentary heat spike can trip an internal temperature limit switch, causing the heater to display an error code when household electricity finally turns back on. In that case, a single push of the Reset button clears the fault cleanly.

What should I do if the screen goes completely black and will not turn on?

First, verify that the electrical outlet has power by plugging in a small household lamp or phone charger. Many water heater outlets feature a built-in GFCI (ground fault circuit interrupter, a safety outlet with test and reset buttons) that can trip during electrical storms. Press the reset button on the wall outlet itself, verify that the circuit breaker in your electrical panel is fully on, and inspect the power cord for any visible signs of damage.