The Rheem Furnace Error Code 59 indicates a problem with the burner or ignition system that prevents proper operation. This guide explains what the code means, common causes, step-by-step troubleshooting, safety considerations, possible repairs, and tips to prevent future occurrences. The information focuses on practical, safe actions and when to contact a qualified HVAC technician.
| Item | Summary |
|---|---|
| Error Code | 59 |
| Primary Meaning | Ignition/Burner Fault Or Lockout |
| Common Causes | Igniter failure, gas valve issue, flame sensor contamination, airflow restrictions, control board or wiring faults |
| Immediate Action | Reset and observe; check power/gas supply; call licensed technician if persists |
What Error Code 59 Means
Rheem furnaces display error code 59 to indicate the control board detected a fault related to ignition or the combustion sequence. The unit may go into a lockout or repeated trial mode when the expected flame signal does not appear or an unsafe condition is sensed.
How The Furnace Ignition Sequence Works
Understanding the ignition sequence clarifies why code 59 occurs. When a call for heat is received the furnace starts a series of steps: inducer motor runs, pressure switches verify venting, gas valve opens, igniter heats or spark occurs, and the flame sensor confirms combustion. A fault at any of these stages can trigger code 59.
Common Causes Of Code 59
Several issues commonly trigger the error. Igniter failure or weak ignition is frequent. A contaminated or failing flame sensor can prevent flame detection. Gas supply problems or a faulty gas valve will stop ignition. Airflow restrictions, blocked vents, and pressure switch issues also interfere with the combustion sequence. Wiring or control board faults and corrosive environments may contribute.
Safety First: Precautions Before Troubleshooting
Safety is paramount. Turn off power to the furnace at the switch and circuit breaker before inspecting internal components. If gas odor is present, evacuate and call the gas company or emergency services. Only qualified technicians should perform gas valve replacements, igniter electrics, or control board work.
Basic Troubleshooting Steps Homeowners Can Safely Try
These initial checks are safe for most homeowners and often resolve simple issues.
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Power And Thermostat: Confirm the thermostat is set to heat and battery-powered thermostats have fresh batteries. Verify the furnace switch and circuit breaker are on.
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Gas Supply: Make sure the gas shutoff valve to the furnace is open. If other gas appliances work while the furnace does not, the issue is likely furnace-specific.
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Reset The Furnace: Many Rheem units allow a reset by turning power off for 30 seconds and back on. Observe the ignition sequence; one reset is acceptable, but repeated resets can stress components.
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Air Filter And Vents: Replace dirty filters and ensure supply/return vents are open. Restricted airflow can affect flame sensing and combustion.
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Condensate And Vents: For high-efficiency furnaces check the condensate trap and PVC vent for blockages or ice in cold weather.
Inspecting The Igniter And Flame Sensor (Technically Simple Checks)
Visual checks of the igniter and flame sensor can reveal obvious problems. With power off, inspect for cracks or visible damage to an igniter and for heavy black or white buildup on the flame sensor rod. Light surface contamination can often be cleaned with fine steel wool or a flame sensor cleaner, but replacements are required for cracked or worn igniters.
When To Replace The Igniter Or Flame Sensor
If the igniter fails to glow or spark during the ignition sequence, replacement is typically required. Flame sensors that continue to trigger faults after cleaning should be replaced. Replace components with OEM or compatible parts and ensure correct installation torque and wiring to avoid further faults.
Gas Valve, Pressure Switches, And Venting Issues
A stuck or failing gas valve prevents gas flow even if the igniter works. Pressure switch failures or blocked venting (including bird nests, debris, or ice) will halt the furnace during the safety checks. These problems often require a licensed HVAC technician to diagnose with manometers and pressure testing equipment.
Control Board, Wiring, And Sensor Faults
Control boards monitor the ignition sequence and error codes. Corroded terminals, frayed wiring, or moisture-related faults can produce error 59. A visual inspection for burnt components or loose connectors is useful, but board-level diagnostics should be performed by professionals to avoid damage.
Interpreting Blinking Lights And Diagnostic LEDs
Rheem furnaces often use LED blinking sequences alongside the numeric code. Counting flashes and consulting the model-specific manual helps pinpoint whether the control board detected low flame signal, ignition failure, or system lockout. Documenting the exact blink pattern before calling service speeds up diagnosis.
Reset Procedure And How Long To Observe
Resetting may clear a transient issue. Turn off power for at least 30 seconds and restore; then observe two full startup cycles. If code 59 returns immediately or after a short run, the problem persists and further diagnosis is required. Limit resets to avoid wear and gas cycling concerns.
When To Call A Qualified HVAC Technician
If code 59 persists after basic checks, or if there is a gas odor, call a licensed HVAC professional. Technicians will perform pressure checks, test the gas valve, examine the ignition control, and may use a combustion analyzer to ensure safe and efficient operation. Complex electrical or gas component replacements should not be attempted by unqualified persons.
Typical Repairs And Estimated Costs
Costs vary by region and furnace model, but common repairs include:
| Repair | Typical Cost Range (Parts + Labor) |
|---|---|
| Flame Sensor Clean Or Replace | $75–$200 |
| Igniter Replacement | $150–$350 |
| Gas Valve Replacement | $300–$700+ |
| Pressure Switch Or Vent Repair | $150–$400 |
| Control Board Replacement | $250–$800 |
Preventive Maintenance To Avoid Error 59
Regular maintenance reduces the risk of ignition faults. Recommended actions include annual professional tune-ups, timely air filter changes, keeping vents and flue clear, protecting the furnace from moisture and pests, and scheduling inspections if the system cycles unusually. A maintenance plan often includes cleaning the flame sensor and inspecting the igniter before cold weather.
Model-Specific Considerations And Manuals
Rheem has multiple furnace models and control boards. Always reference the specific model’s wiring diagram and error code table in the owner’s manual. Manufacturer resources and model-specific forums can provide additional diagnostic steps tailored to the unit in question.
Key Takeaways And Quick Troubleshooting Checklist
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Code 59 Signals An Ignition Or Burner Fault: It often means the flame signal is missing or the combustion sequence failed.
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Perform Safe Preliminary Checks: Check power, thermostat, gas supply, filters, vents, and reset once.
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Clean Or Inspect Flame Sensor And Igniter: Clean mildly contaminated sensors; replace cracked igniters.
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Call A Licensed Technician For Gas Valve, Pressure, Or Board Issues: These require specialized tools and expertise.
Resources And Further Reading
Owners should consult the Rheem furnace manual, the model-specific error code tables, and manufacturer technical bulletins. For safety, contact local licensed HVAC professionals for inspections, repairs, and combustible gas emergencies.
Note: This article provides general guidance and does not replace professional diagnosis. Working on gas and electrical components can be dangerous; when in doubt, contact a qualified service provider.