Can I keep running the equipment with this fault active?

Generally no. Faults on Water heater units are emitted when a sensor, safety, or control circuit is outside its operating envelope. Running through an active fault risks compressor, heater, or control-board damage. Diagnose and clear the fault first.

What part is most commonly replaced for Rinnai Tankless Water Heater Igniter / Electrode Replacement?

The most frequently replaced parts for Rinnai Tankless Water Heater Igniter / Electrode Replacement are listed in the Parts Reference section of this guide with OEM part numbers and typical price ranges. Check the table for direct replacements.

Is Rinnai Tankless Water Heater Igniter / Electrode Replacement a DIY repair or do I need a technician?

Sensor swaps, fan motor replacements, and condenser cleaning are typical DIY-level repairs. Anything involving refrigerant, gas, or high-voltage (>240V) work requires a licensed technician for both safety and code-compliance reasons.

Rinnai Tankless Water Heater Igniter / Electrode Replacement

Q: What does Rinnai Tankless Water Heater Igniter / Electrode Replacement mean?

Ignition failure codes, no hot water, clicking without ignition, and sooty flame rod tips mean the igniter or electrode needs cleaning or replacement.

Q: How do I fix Rinnai Tankless Water Heater Igniter / Electrode Replacement?

Follow the step-by-step diagnosis below. The most likely fix is identified by checking power, sensor resistance, and control-board signals in order — using a multimeter and the part numbers documented in the parts reference table.

Rinnai Tankless Water Heater Igniter / Electrode Replacement — What This Part Does

The igniter produces the spark that lights the gas burner when your tankless water heater calls for heat. The flame rod electrode then senses that flame and signals the control board that combustion is happening safely. When either component gets coated with carbon or sulfur buildup, or when the electrode tip wears out, the unit cannot prove flame and will lock out with an ignition fault code. The control board opens the gas valve and energizes the igniter, but if the flame rod does not detect flame within a few seconds, the system shuts down and displays an error. Most ignition problems come from carbon deposits on the electrode or igniter tip, but cracked insulators or worn tips also cause these faults after years of service.

Jump to Replacement Steps

Signs It Needs Replacing

Ignition failure or lockout codes displayed The unit shows an ignition-related error code and will not fire, even though you hear the fan run and the igniter click.
Clicking or sparking sound but no flame You hear the igniter sparking repeatedly, but the burner never lights and the unit times out.
Black or white deposits on electrode or igniter tip When you open the burner compartment, the flame rod or igniter shows heavy carbon, soot, or white sulfur buildup on the metal tip.
Unit fires briefly then shuts off immediately The burner lights for a moment, then the control board cuts gas because the flame rod cannot sense flame through the contamination.
Intermittent hot water or random lockouts The heater works sometimes but throws ignition faults randomly, especially after sitting idle or during cold weather.
Cracked or discolored igniter insulator The ceramic insulator around the igniter electrode shows cracks, chips, or brown discoloration from heat stress.

How to Replace It

Shut off electrical power at the breaker and close the gas isolation valve to the water heater.
Remove the front cover panel by lifting or unscrewing the fasteners, then set it aside.
Take off the burner access cover or combustion chamber cover, noting the position of any gaskets or seals.
Locate the igniter and flame rod electrode inside the burner box (the igniter will have a ceramic insulator and a single wire, the flame rod is a thin metal rod with a wire connector).
Disconnect the wire connector from each component, then unscrew the mounting bracket or fastener holding the igniter and flame rod in place and pull both assemblies straight out.
Inspect the tips for heavy carbon or damage, and if cleaning is appropriate, gently wipe the metal electrode and igniter tip with a Scotch-Brite pad or fine abrasive (do not gouge or scrape aggressively), otherwise install the new OEM igniter and flame rod assembly.
Replace the burner cover gasket or seal with the new one included in the kit, then reinstall the burner cover and align all screw holes and brackets carefully.
Reconnect the igniter and flame rod wires to their connectors, then reinstall the front cover panel.
Open the gas valve, restore electrical power, and test the unit by calling for hot water and verifying normal ignition and flame detection.

The Part You Need

Part	Notes
Rinnai OEM igniter / flame rod electrode kit	Amazon \| Check your model and serial number on the rating plate inside the front cover or on the right side of the unit. Order the OEM kit by model series (examples include kit 104000192-K for R75/R94 series). Some kits include both igniter and flame rod, others are sold separately.
Burner cover gasket or seal	Amazon \| Often included with the OEM electrode kit. If not, order separately by model number to maintain proper combustion chamber sealing.

When to Call a Pro

Gas appliance ignition and combustion work requires careful handling of electrical spark components, gas connections, and sealed combustion chambers. If you are not comfortable working with gas valves, wiring, or reassembling burner covers with proper gasket seals, hire a licensed technician. Also call a pro if cleaning the electrode and igniter does not restore ignition, if you see cracked heat exchangers or other damage inside the burner box, or if the unit continues to lock out after you replace the igniter and flame rod. Incorrect reassembly or a missed gasket can create unsafe combustion conditions or carbon monoxide risk. For gas line, burner, or igniter work, or if you ever smell gas, stop and call a licensed technician.