Noritz Water Heater Priority Light Flashing Fix

Quick Answer

A flashing Priority light on a Noritz water heater typically signals a scheduled maintenance reminder or a communication error between units. The most common fix is resetting the service timer or checking the remote controller wiring connections.

That flashing Priority light is either a maintenance reminder, usually after about 1,000 hours of runtime or 12 months since last reset, or a sign that two linked units can't talk to each other properly. Ignore it and you'll eventually hit a lockout right when you need hot water most. I've seen people put this off for months and then wonder why their heat exchanger's coated in calcium scale.

NoritzWaterheaterSeverity: moderate80% DIY Success

Time to Fix

10–30 min

Difficulty

beginner

Parts Cost

$40 – $90

Tools Needed

Flashlight, Phillips #2 screwdriver

What Does the PRIORITY-LIGHT Code Mean?

OK so here's what's actually going on. Most people don't realize the Priority button is a safety lockout, not just a status indicator. Only the remote with that light on can change the water temperature, which is why your buttons won't respond if another controller in the house has Priority status. Takes seconds to fix. But a flashing Priority light is a different story and usually means a maintenance timer or a wiring hiccup.

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

Scheduled service reminder activated after 1 year or set interval40%

Active error code displayed alongside Priority light24%

Controller wiring or communication issue22%

Unit configured as Priority unit in multi-unit installation14%

Symptoms You May Notice

The green Priority light is flashing steadily, not solid, and nobody in the house touched anything.
You've got full hot water flowing fine but the light won't stop blinking and you can't figure out why.
Priority light is flashing at the same time a number like 11, 12, or 90 shows up on the display screen.
Buttons on your remote are completely unresponsive and the Priority light isn't lit on your controller at all.
Light came on solid right around the one-year mark after install, out of nowhere.

Can you reset a Noritz waterheater to clear the PRIORITY-LIGHT code?

To clear a maintenance flash, hold the Up and Down arrows simultaneously for 5 seconds while the unit's in standby, then navigate to the reset option in the service data menu and confirm. Counter resets and you're good for another year. For a Priority handoff, press the Priority button on whichever remote you want in charge. If the light's still flashing after both attempts, cycle the breaker for 30 seconds, then try the button sequence again.

Tools Required for Diagnosis

FlashlightPhillips #2 screwdriverFine-grit sandpaper (for cleaning corroded terminals)Multimeter (optional, for checking wire continuity)

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

Replacement Parts

If your diagnostic testing proves the component has failed, you will need a replacement. We recommend OEM parts over aftermarket for water-handling components.

Part Name	OEM Number	Estimated Price
Remote Controller (RC-7651M)RC-7651M · $40–$90	RC-7651M	$40 – $90

Frequently Asked Questions

What does the Priority light mean on a Noritz water heater?

Think of it like the driver's seat indicator. In a house with multiple remotes, only the one with the light on can change the temperature. That's what prevents someone in the kitchen from accidentally scalding someone in the shower. If it's flashing though, it's usually the unit saying it's time for its annual descaling, or that a fault code is active and it's trying to wave you down. Either way, don't ignore a flashing Priority light for more than a week or two.

How do I turn off the Priority light on my Noritz?

If it's solid, you usually don't want to turn it off. You just want to move it to a different remote by pressing the Priority button there. If it's flashing because of a service reminder, a simple power reset won't do the trick. You've got to run the specific button sequence for your model, which is usually holding the flow alarm button for 5 seconds, or have a tech reset the maintenance counter after doing a proper vinegar flush of the heat exchanger.

Can the Priority light flash without any actual fault?

Yeah, that happens pretty regularly. A loose communication wire between the heater and the remote can cause that light to flicker on and off. It's not a fault in the sense that your heater's broken, but it does mean the remote's dropping its connection for a split second here and there. Check those terminal screws inside the unit first. They should be genuinely firm, not just snug. If one of them is barely finger-tight, tighten it down and see if the flicker stops within a few minutes.

My Noritz Priority light came on exactly one year after installation. Is that a service reminder?

That's a textbook Noritz service reminder. They build a timer right into the logic board to prompt you to descale. Tankless heaters are way more sensitive to hard water than tank heaters, so this light is your early warning system. A proper flush now costs you maybe two hours and a jug of white vinegar. A clogged heat exchanger in three years is $300 to $700 in parts and labor, or honestly just the whole unit depending on how bad it got. Do the flush.

Can I change which unit is Priority in a multi-unit Noritz setup?

Absolutely. Just walk up to whichever remote you want in charge and press the Priority button. The light should hop right over and you'll have temperature control from that remote. One thing though: if hot water's actively running when you try this, some models won't let you hand off Priority while the burner's firing. Wait for the demand to stop completely, try it again, and it should work fine. If it still won't transfer, check if there's an active fault code locking the primary unit in place.

Related Noritz Waterheater Error Codes

Code: HUBNoritz Tankless Water Heater Error Codes: Complete NR and NRCP Series Guide Code: TROUBLESHOOTINGNoritz Tankless Water Heater Troubleshooting: 8 Common Problems and Fixes Code: RESETHow to Reset a Noritz Tankless Water Heater and Clear Error Codes

Models Known to Experience PRIORITY-LIGHT Errors

This repair applies to most Noritz waterheaters with this error code. Common model numbers include:

NRCP199-DV, NRCP111-DV, NR98-DV, NR66-DV, NR711, NR981-DV, NRCP542, NCC199CDV

Written by

Raj Patel

HVAC & Water Systems Specialist · 15 years experience

Last verified for technical accuracy on March 14, 2026