Noritz Water Heater Ignition Failure: No Error Code

Quick Answer

When a Noritz tankless water heater fails to ignite with no error code on the display, the most common culprits are a gas supply that has been turned off or interrupted, a dirty flame rod that cannot form an ionization signal, a spark gap on the igniter that has widened from wear, and gas supply pressure too low to support combustion.

In the field, a Noritz sitting silent without a code is usually stuck at the very first gate of the ignition sequence. If the flow sensor doesn't see enough water movement, the computer never even tries to spark, which is why you don't see a Code 11 or 12. It's a frustrating ghost symptom that usually points to a plumbing restriction or a sensor that's gone blind to water flow.

NoritzWaterheaterSeverity: highDifficulty: intermediate76% DIY Success

Time to Fix

20–75 min

Difficulty

intermediate

Parts Cost

$12 – $35

Tools Needed

Phillips #2 screwdriver, Fine steel wool (000 grade)

What Does the IGN-FAILURE Code Mean?

Most homeowners expect a flashing red light when things go wrong, but a Noritz can stay perfectly dark even when it refuses to fire. When I run into this, I start by checking the Maintenance Monitor to see if the unit even knows you turned the tap on. If the control board doesn't see the flow, it won't even attempt to light the burner.

Most Likely Causes

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

Gas supply turned off or supply valve partially closed40%

Dirty or oxidized flame rod preventing ionization signal24%

Gas supply pressure too low to sustain ignition attempt22%

Spark igniter electrode gap too wide from wear14%

Symptoms You May Notice

You turn on the hot water tap, wait 30 seconds, and get nothing but cold water while the display sits completely blank or shows normal standby with zero error code.
You can hear the unit clicking like it's trying to spark, but no flame catches and it goes quiet again after a few seconds.
The unit fires up maybe one out of every five tries, so you can never predict when it'll actually work and your shower starts cold most mornings.
Flow at the tap is noticeably reduced even though there's no error code showing, and the water that does come out never gets above lukewarm.

Can you reset a Noritz waterheater to clear the IGN-FAILURE code?

To clear the logic board, unplug the power cord or flip the dedicated breaker for a full 60 seconds. While the power is off, ensure all hot water taps are closed. Plug the unit back in and wait for the display to initialize completely before attempting to draw hot water again. This forced reboot often clears logic loops that prevent the sequence from starting.

Tools Required for Diagnosis

Phillips #2 screwdriverFine steel wool (000 grade)Feeler gauge (3-4mm range)Combustible gas detectorFlashlight or headlampMultimeter (optional, for voltage checks at igniter)

Service / Diagnostic Mode

Hold Temp Up and Temp Down buttons simultaneously for 3 seconds until the display enters maintenance monitor mode, then use the arrow buttons to scroll through stored error codes.

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
Flame Rod (Flame Sensor)100001706 · $12–$25	100001706	$12 – $25
Spark Igniter Assembly100001714 · $20–$35	100001714	$20 – $35

Frequently Asked Questions

Why would a Noritz fail to ignite with no error code?

It comes down to the logic board's programming. If the flow sensor doesn't report at least 0.5 gallons per minute, the computer thinks the water is still off. Since it doesn't think it needs to work, it won't trigger an error code for failing to work. It's like a car that won't start because it doesn't realize you turned the key. Always check for a scaled-up flow sensor or a clogged faucet aerator first before you go pulling the unit apart.

How is this different from the Noritz Code 11 guide?

A Code 11 means the heater tried to light three times and failed, so it threw a red flag. When you've got no code, the heater usually isn't even trying. This guide covers the pre-flight stuff like water flow and power logic that happens before the spark ever clicks. If you hear clicking but see no code, your controller might be resetting mid-cycle from a voltage drop before it even gets a chance to log the fault.

My Noritz ignites sometimes but fails most of the time. What causes intermittent ignition failure?

Intermittent ignition is almost always a dirty flame rod or a struggling gas regulator. As the rod warms up during operation, the oxidation layer expands and can eventually block the signal entirely. I also see this a lot when the exhaust vent is partially blocked by a bird nest or debris, which causes the unit to try and light, realize it can't breathe, and shut down before it even has time to process an error code. Clean the flame rod first. Seriously, that fixes it probably 60% of the time.

Can I clean the flow sensor myself or do I need a tech?

Yeah, you can do it yourself if you're reasonably comfortable with basic plumbing. Shut off the water supply valves on both sides of the unit, disconnect the cold water inlet, and find the flow sensor inline on that pipe. There's a small turbine inside that spins as water passes through. Soak the whole sensor in white vinegar for 30 minutes to dissolve the scale, rinse it well, and reinstall. Don't use anything abrasive or you'll damage the turbine. If you're not comfortable with plumbing connections, a tech visit for this runs about $85-120 depending on your area.

How much does it cost to fix a Noritz that won't ignite?

Depends on what's actually broken. Dirty flame rod? Basically free, just some steel wool. Igniter electrode replacement runs $45-90 for the part plus an hour of labor if you hire it out. A flow sensor replacement is usually $60-150 depending on your model. Worst case, a failed control board can run $300-500 installed. But honestly, most of the time I show up to one of these and it's a half-closed gas valve or a flame rod that needs two minutes of cleaning. Start with the simple stuff first.

Related Noritz Waterheater Error Codes

Code: HUBNoritz Tankless Water Heater Error Codes: Complete NR and NRCP Series Guide Code: 11Noritz Code 11: No Ignition Fix for NR and NRCP Series Code: 12Noritz Code 12: Flame Failure During Operation Code: RESETHow to Reset a Noritz Tankless Water Heater and Clear Error Codes

Models Known to Experience IGN-FAILURE 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, NRC111-DV, NRC98-DV, NRCP98-DV

Written by

Raj Patel

HVAC & Water Systems Specialist · 15 years experience

Last verified for technical accuracy on March 14, 2026