Rinnai Code 63: Combustion Fan Error

Quick Answer

Rinnai Code 63 indicates a combustion fan fault where the blower fails to reach the required speed for ignition. The most common fix is clearing debris from the fan intake or replacing a faulty fan motor assembly.

While a Rinnai Code 63 often points to a mechanical fan failure, field technicians frequently find that simple obstructions like bird nests or dust buildup are the true culprits. This error prevents the ignition sequence for safety, so checking the intake vent and fan motor wiring should be your first step before replacing expensive components.

RinnaiWaterheaterSeverity: highDifficulty: intermediate70% DIY Success

Time to Fix

30–120 min

Difficulty

intermediate

Parts Cost

$30 – $150

Tools Needed

Phillips #2 screwdriver, Flat-head screwdriver

What Does the 63 Code Mean?

Think of this as a breathing problem for your water heater. Before the gas even flows, Rinnai checks if the blower can move enough air. If you're hearing the fan rev up and down or struggling to stay consistent, you're probably looking at mechanical drag or a sensor that's gone haywire. Most of the time we can sort this out without buying expensive parts.

Most Likely Causes

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

Fan air intake blocked by lint, debris, or insect nest40%

Combustion fan motor failing and unable to reach required RPM24%

Fan speed sensor (Hall effect sensor) reporting incorrect data14%

Partial vent obstruction causing fan to work against backpressure12%

Loose or corroded wiring connector to fan assembly10%

Symptoms You May Notice

Code 63 on controller display
No hot water, unit shuts down immediately after demand
Audible fan noise that sounds labored or slower than normal
Fan starts then stops before ignition sequence completes
No fan sound at all when demand is triggered

Can you reset a Rinnai waterheater to clear the 63 code?

Cycle the power button on your controller first. If the code sticks, flip the breaker off and leave it for 30 seconds. That forces the control board to re-calibrate from scratch. After you restore power, wait a full minute before calling for hot water. Just know that if the blockage or motor drag is still there, it'll come right back the second you open a tap.

Tools Required for Diagnosis

Phillips #2 screwdriverFlat-head screwdriverDigital multimeterVacuum with brush attachmentBright flashlight or headlampElectrical contact cleaner sprayNeedle-nose pliers

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
Combustion Fan / Blower Motor AssemblyContact Rinnai with model number · $80–$150	Contact Rinnai with model number	$80 – $150
Fan Speed Sensor (Hall Sensor)Contact Rinnai with model number · $30–$50	Contact Rinnai with model number	$30 – $50

Frequently Asked Questions

What is the difference between Rinnai Code 63 and Code 61?

Think of Code 61 as a dead motor and Code 63 as a struggling one. With 61, the fan usually won't move at all because the motor's burnt out. With 63, the fan's trying to work but can't hit the specific RPM target the computer wants to see. That's why 63 is often just a blockage or a sensor thing, while 61 almost always means you're buying a new blower motor.

Can I clean the Rinnai combustion fan intake myself?

You definitely can, and honestly it's one of the few maintenance tasks I actively encourage homeowners to handle themselves. Just make sure the power's off first. Use a vacuum with a brush attachment on the intake screen. If you've got to reach inside the unit to pull out a bird's nest or heavy debris, be gentle around the wiring. It's a 10-minute job that can save you a $200 service call.

How often should I check the Rinnai combustion fan intake?

I tell customers to check it every time they change their furnace filters. If your Rinnai's in a laundry room or a garage, it's going to suck in lint and dust way faster than one tucked in a utility closet. At a minimum, give it a look once a year. Keeping that intake clean is probably the single best thing you can do to extend the life of the combustion fan motor.

My Code 63 only appears in summer. Why?

It's almost always bugs. Mud daubers and wasps love the warmth of the intake vent and they can build a nest solid enough to trigger a Code 63 in just a weekend. If your unit is outside or vents to a low spot on the house, check those vent terminations first before you start taking anything apart. I've pulled nests out of those caps that were the size of a softball.

Is Code 63 a DIY repair or does it need a technician?

If it's just cleaning out debris or reseating a loose wire connector, go for it. Replacing the fan motor is about a 4 out of 10 on difficulty. It's just a few screws and a plug. But if you think the main control board's involved, or if you're not comfortable using a multimeter on a live circuit, call a pro. Don't guess on board replacements, those things run $300 and up.

Related Rinnai Waterheater Error Codes

Code: HUBRinnai Tankless Water Heater Error Codes: Complete Guide Code: 61Rinnai Code 61: Combustion Fan Motor Failure Code: 55Rinnai Code 55: Combustion Abnormality Detected Code: RESETHow to Reset a Rinnai Tankless Water Heater: All Models Guide

Same Fix on Other Brands

Navien waterheaterE110: Navien E110 Error Code: Exhaust Blockage and Venting Fault Explained

Models Known to Experience 63 Errors

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

RUR98iN, RU199iN, RU98eN, V65iN, RL75iN, RU160iP

Written by

Raj Patel

HVAC & Water Systems Specialist · 15 years experience

Last verified for technical accuracy on March 14, 2026