MEDIUM URGENCY

Rheem Code 22 - High Limit Switch Fault

Code 22

High limit switch open - overheating. Usually restricted airflow.

Brand: Rheem (Also covers Ruud) | Equipment: Gas Furnace

What This Code Means

Code 22 means the high temperature limit switch has tripped. The heat exchanger got too hot, so the safety switch shut off gas to prevent damage.

Likely Causes (Ranked)

Most common (~70%)

Dirty air filter

What: Restricted airflow lets heat build up.

How to check: Inspect filter.

Fix: Replace filter, cycle power.

Shop parts

Common

Closed registers

What: Static pressure spike.

How to check: Open all vents.

Fix: Clear vents and returns.

Common

Failed blower motor

What: Weak blower can't carry heat.

How to check: Listen for blower at heat call.

Fix: Test capacitor, replace motor.

Shop parts

Diagnostic Steps

Cut power 30s
Replace filter
Open all vents
Wait for cooldown
Watch for return

Frequently Asked Questions

Why does Rheem code 22 keep coming?

Furnace overheating. Filter resolves 70% of cases.

Same on Ruud?

Yes.

DIY fix?

Filter and vents yes.

Related Rheem Codes

Related Symptoms

Need More Help?

Try our interactive symptom diagnostic tool or browse Rheem parts.

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