Rheem Furnace Error Code 22: Causes, Troubleshooting, and Repair Steps

Rheem Furnace Error Code 22 Signals A Flame Failure Or Ignition Problem On Many Rheem And Ruud Gas Furnaces. This Article Explains The Common Causes, Safe Troubleshooting Steps, Diagnostic Tests, And When To Call A Professional.

Item	Quick Summary
Error Meaning	Ignition Or Flame Failure (Flame Not Detected After Ignition Sequence)
Common Causes	Dirty Flame Sensor, Faulty Ignitor, Gas Valve Issue, Venting/Combustion Air Problems, Control Board Or Wiring Fault
Safety Priority	Shut Down Gas Supply And Power If Smell Of Gas; Follow Manufacturer Guidelines

What Rheem Furnace Error Code 22 Means

Error Code 22 On Many Rheem Furnaces Typically Indicates A Flame Failure Or Ignition Fault Detected By The Furnace Control Board. During The Ignition Sequence, The Control Expects To See A Flame Signal Within A Specific Time Window; If The Flame Sensor Does Not Detect A Flame, The Board Logs Code 22 And Locks Out Or Reattempts Ignition Depending On Model Settings.

This Code Applies To Multiple Rheem/Ruud Models Using Direct Spark Ignition (DSI) Or Hot Surface Ignitors, So Specific Behavior Can Vary By Unit.

Common Causes Of Code 22

1. Dirty Or Faulty Flame Sensor

The Flame Sensor Detects The Presence Of Combustion Via A Small Metal Rod Inside The Burner Box. Carbon Or Oxidation Buildup Can Prevent A Clean Signal, Causing The Board To Think No Flame Is Present.

2. Faulty Ignitor Or Ignition Component

Cracked Hot Surface Ignitors Or Weak Spark In DSI Systems Can Fail To Produce Reliable Ignition, Resulting In Repeated Attempts And A Flame Failure Code.

3. Gas Supply Or Gas Valve Issues

Insufficient Gas Pressure, Closed Valves, Or A Defective Gas Valve Can Prevent Proper Flame Establishment Even If The Ignitor Functions Correctly.

4. Venting, Combustion Air, Or Pressure Switch Problems

Blocked Exhaust, Restricted Combustion Air, Or A Faulty Pressure Switch Can Interrupt The Combustion Sequence And Trigger An Ignition Lockout.

5. Control Board Or Wiring Faults

Damaged Wiring, Loose Connections, Or A Defective Furnace Control Board Can Produce False Flame Failure Readings And Cause Error Code 22.

Safety First: Before Troubleshooting

Safety Is Paramount When Working With Gas Furnaces. If There Is A Strong Smell Of Gas, Evacuate The Area And Call The Gas Company Or Emergency Services Immediately.

Always Turn Off Power To The Furnace At The Breaker And Close The Gas Valve Before Performing Any Internal Inspections. If The User Is Uncomfortable Or Unsure, Contact An HVAC Professional.

Step-By-Step Troubleshooting For Rheem Furnace Error Code 22

Tools And Supplies Recommended

• Screwdrivers And Nut Drivers
• Multimeter (Volts/Ohms)
• Fine Sandpaper Or Steel Wool
• Gloves And Safety Glasses
• Manufacturer Manual Or Model-Specific Wiring Diagram

1. Record Error Behavior And Perform A Reset

Note The Furnace Display Lights And How Many Times It Attempts Ignition Before Locking Out. A Simple Reset — Cycling Power Off For 30 Seconds — Can Clear Temporary Faults.

2. Inspect The Flame Sensor

Remove The Flame Sensor From The Burner Tube Using A Screwdriver. Visually Inspect For Black Carbon Or White Oxidation. Clean Lightly With Fine Sandpaper Or Steel Wool, Wipe With A Dry Cloth, Reinstall, And Retry Operation.

Tip: Do Not Excessively Sand Or Bend The Sensor Rod; Damage Can Cause False Readings.

3. Check The Ignitor

For Hot Surface Ignitors, Inspect For Visible Cracks Or Breaks. Use A Multimeter To Test Resistance Against Manufacturer Specs. A Broken Or Weak Ignitor Should Be Replaced.

4. Inspect The Burners And Gas Valve

Ensure Burners Are Clean And Properly Seated. Check That The Main Gas Valve Is Open. If The Furnace Smells Like Gas Or Burners Do Not Light, Stop And Call A Professional.

5. Test The Flame Signal With A Multimeter

With The Furnace In Run/Trial For Ignition, Measure The Flame Sensor Output Voltage/Current Per The Service Manual. A Weak Or Absent Signal Indicates Sensor, grounding, or board issues.

6. Verify Pressure Switch And Venting

Inspect Intake And Exhaust Vents For Blockage. Test The Pressure Switch For Proper Operation And Check For Cracks In PVC Venting That Could Affect Pressure Readings.

7. Inspect Wiring And Control Board

Look For Loose Connectors, Frayed Wires, Or Burn Marks On The Control Board. Use A Multimeter To Verify Voltage To Ignitor And Gas Valve During The Ignition Sequence.

8. Run A Controlled Test After Repairs

After Cleaning Or Replacing Components, Restore Power And Observe Several Ignition Cycles. Confirm That The Furnace Lights Properly And That Error Code 22 Does Not Reoccur.

When To Replace Components Versus Call A Technician

Cleaning The Flame Sensor And Replacing A Visible Broken Ignitor Are Common DIY Repairs If The User Is Comfortable With Basic Tools And Safety Procedures.

Replace The Gas Valve, Control Board, Or Perform Gas Pressure Adjustments Only With Professional HVAC Service. If Code 22 Persists After Basic Steps, Contact A Licensed Technician To Avoid Safety Risks.

Common DIY Fixes And Approximate Costs

Item	Typical DIY Cost	Notes
Flame Sensor Cleaning	Free–$10	Most Effective First Step; Low Risk
Flame Sensor Replacement	$20–$80	Sensor Prices Vary By Model
Hot Surface Ignitor Replacement	$30–$120	Relatively Simple Replace; Fragile Item
Professional HVAC Service Call	$75–$200	Includes Diagnostic; Labor Extra For Repairs
Gas Valve Or Control Board Replacement	$250–$900+	Licensed Technician Recommended

Model-Specific Notes And Variations

Rheem And Sister Brand Ruud Use Similar Diagnostic Codes But Behavior Can Vary By Series. Some Models Will Attempt Multiple Ignitions Before Lockout; Others Immediately Enter A Lockout Requiring Manual Reset.

Consult The Furnace Model’s Installation/Service Manual For Exact Error Code Definition, Ignition Sequence Timings, And Wiring Diagrams To Ensure Accurate Troubleshooting.

Preventive Maintenance To Reduce Error 22 Recurrence

• Schedule Annual Professional Tune-Ups To Check Gas Pressure, Combustion, And Electrical Components.
• Replace Air Filters Regularly To Maintain Proper Airflow And Combustion Conditions.
• Keep Furnaces And Vents Clean And Clear Of Debris; Clean Burners As Needed.
• Inspect Flame Sensor And Ignitor Annually; Clean Or Replace Before Failure.

Troubleshooting Checklist For Technicians

1. Verify Error Code 22 On Control Board And Note Number Of Ignition Attempts.
2. Check Flame Sensor Continuity And Output Signal During Ignition.
3. Measure Voltage To Ignitor And Gas Valve During Trial For Ignition.
4. Test Pressure Switch Operation And Confirm Venting Integrity.
5. Inspect For Grounding Issues Or Intermittent Wiring Failures.
6. Perform Combustion Analysis If Needed To Verify Proper Fuel Delivery.

Frequently Asked Questions About Rheem Furnace Error Code 22

Can A Dirty Flame Sensor Cause Code 22?

Yes. A Dirty Or Corroded Flame Sensor Is One Of The Most Common Causes Of Error Code 22 And Is Often Resolved By Cleaning The Sensor.

How Long Will The Furnace Try To Ignite Before Lockout?

Ignition Attempts Vary By Model; Many Units Try 2–3 Times Before Locking Out. Consult The Model Manual For Exact Attempt Counts And Lockout Behavior.

Is It Safe To Keep Resetting The Furnace When Code 22 Appears?

Repeatedly Resetting Without Addressing The Root Cause May Cause Further Damage And Is Not Recommended. Investigate And Repair The Underlying Issue.

Will A Bad Thermostat Cause Error Code 22?

A Faulty Thermostat Rarely Causes A Specific Flame Failure Code, But Incorrect Signals Or Short Cycling Can Influence The Ignition Sequence. Check Thermostat Wiring If Other Causes Are Ruled Out.

Resources And Where To Find Parts

Original Rheem Replacement Parts Are Available Through Authorized Dealers, HVAC Supply Houses, And Reputable Online Retailers. Always Match Part Numbers To The Furnace Model To Ensure Compatibility.

Manufacturer Service Manuals And Wiring Diagrams Provide Model-Specific Diagnostic Information. Rheem’s Official Website And Dealer Network Offer Access To Technical Documents And Support.

Key Takeaways On Rheem Furnace Error Code 22

Error Code 22 Generally Indicates A Flame Detection Or Ignition Failure. Start Troubleshooting By Cleaning The Flame Sensor And Inspecting The Ignitor, Burners, And Gas Supply. Use A Methodical Diagnostic Process And Prioritize Safety.

If Basic DIY Steps Do Not Resolve The Issue, Contact A Licensed HVAC Technician For Gas Valve, Control Board, Or Combustion System Repairs.

Rheem Official Site Provides Product Support And Documentation For Model-Specific Diagnostics.