Navien E012 Error Code: Flame Failure During Operation

Quick Answer

Navien E012 means the unit lit successfully but the flame was extinguished during the heating cycle. The flame rod stopped detecting the ionization signal that confirms an active flame. The leading cause is fluctuating gas supply pressure that drops below the minimum during sustained operation. A dirty or failing flame rod is the second most common cause, identical to E003 diagnosis. Unlike E003, if E012 occurs intermittently (only during heavy demand), suspect a gas supply pressure problem rather than an igniter fault.

NavienWaterheaterSeverity: highDifficulty: intermediate72% DIY Success

Time to Fix

30–90 min

Difficulty

intermediate

Parts Cost

$15 – $200

Tools Needed

Multimeter (DC microamp range for flame rod testing), Fine steel wool (0000 grade)

What Does the E012 Code Mean?

E012 means the Navien fired successfully but the flame died mid-cycle. Gas pressure fluctuation under load is the most common cause. Also check the flame rod for oxide buildup, water flow rate adequacy, and any vent restriction that could snuff the flame.

Most Likely Causes

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

Gas pressure dropping below minimum during high-demand operation40%

Dirty or worn flame rod losing ionization signal mid-cycle24%

Water flow rate dipping below 0.5 GPM minimum during the draw14%

Gas valve solenoid intermittently closing under vibration12%

Partial vent restriction reducing combustion air supply10%

Symptoms You May Notice

E012 on display after unit was already producing hot water
Hot water suddenly goes cold mid-shower or mid-use
Unit fires and works for 1-5 minutes then shuts off with E012
Error occurs more frequently when other gas appliances run simultaneously

Can you reset a Navien waterheater to clear the E012 code?

After each E012 incident, reset by pressing the Info button 3 times. If E012 is recurring, do not continue to reset without identifying the cause. Each flame loss event during operation can cause slight thermal stress on burner components. A hard reset (breaker off 30 seconds) can clear a stuck fault state, but does not fix the underlying problem.

Tools Required for Diagnosis

Multimeter (DC microamp range for flame rod testing)Fine steel wool (0000 grade)Manometer (for gas pressure testing)FlashlightCombustible gas detector

Diagnostic Checklist

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

Determine if E012 is random or pattern-based

Determine if E012 is random or pattern-based. Does it happen only during high-demand situations (multiple fixtures open, furnace running simultaneously)? If yes, gas pressure under load is the primary suspect. If it happens even at low demand, the flame rod or igniter system is more likely at fault.

Inspect and clean the flame rod using the same procedure as for E003

Check gas pressure at the unit

Check the vent termination for any partial blockage

Verify that water flow rate stays consistently above 0.5 GPM

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 Assembly (NPE series)30013968A · $15–$30	30013968A	$15 – $30
Gas Valve Assembly30010696A · $120–$200	30010696A	$120 – $200
Condensate Trap Kit30010723A · $20–$35	30010723A	$20 – $35

Verify part fitment for your Navien model

Repair vs. Replace Calculator

Appliance Age (Years)7 Yrs

Labor Approach

Our Verdict

REPAIR

Estimated Cost: $108 (Parts) vs $1100 (New Machine)

Frequently Asked Questions

Why does my Navien give E012 only in winter when the furnace is running?

Running both the furnace and water heater simultaneously puts a high demand on your gas supply line. If the gas supply pipe to your home is undersized, or if there is a pressure regulator that struggles under combined load, the inlet pressure at the Navien can drop below the 3.5 inches WC minimum. The unit lights because pressure is adequate at ignition, but as the furnace stays on, available pressure drops and the water heater flame extinguishes. A licensed plumber can measure dynamic pressure under load to confirm this.

Is E012 dangerous?

E012 itself is a controlled safety shutdown. The unit detected flame loss and shut off the gas valve, which is the correct safe response. The underlying causes of E012 (low gas pressure, partial vent blockage) should be diagnosed promptly because they can worsen over time. Do not disable or repeatedly bypass this error code without repair.

What is the difference between E012 and E003 on a Navien?

E003 means the unit attempted to ignite and failed on all 3 tries, so combustion never started. E012 means combustion started successfully and then stopped unexpectedly during the heating cycle. The flame rod and gas pressure are suspects in both cases, but E012 points more toward intermittent conditions (pressure fluctuation, flow dropout) while E003 more often points to a consistently failed component (badly oxidized flame rod, cracked igniter).

Can I fix E012 myself or do I need a technician?

Cleaning the flame rod is a DIY-friendly first step and resolves E012 in about 30% of cases. Checking and cleaning aerators and the inlet filter are also DIY tasks. However, testing gas pressure under load requires a manometer and knowledge of safe gas handling, and any gas valve or PCB replacement should be done by a licensed technician. If cleaning the flame rod does not resolve E012 within 48 hours, schedule a professional visit.

My Navien gives E012 after exactly 3 minutes every time. What causes that?

A consistent time-based failure pattern often indicates a thermal issue rather than a random component fault. The most likely culprit is a flame rod that begins to fail as it heats up (thermal coefficient failure in the ceramic insulator) or a gas valve that closes when it reaches operating temperature due to a degraded solenoid coil. A consistent 3-minute cutoff is unusual enough to warrant a professional diagnosis, as it may point to a gas valve that needs replacement.

Related Navien Waterheater Error Codes

Code: HUBNavien Tankless Water Heater Error Codes: Complete NPE and NCB Series Guide Code: E003Navien E003 Error Code: Ignition Failure Fix for NPE and NCB Series Code: E001Navien E001 Error Code: Ignition Failure (First Attempt)Code: RESETHow to Reset a Navien Tankless Water Heater and Clear Error Codes

Models Known to Experience E012 Errors

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

NPE-240A, NPE-180A, NPE-210A, NCB-240E, NPN-199A

Last verified for technical accuracy on March 14, 2026