MEDIUM URGENCY

Rheem Code 11 - Ignition Failure

Code 11

Burners failed to ignite after multiple attempts.

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

What This Code Means

Code 11 means the Rheem (or Ruud) furnace attempted ignition multiple times but no flame was established. Common after 3 failed retries.

Likely Causes (Ranked)

Most common (~50%)

Dirty flame sensor

What: Sensor coated, can't detect flame.

How to check: Pull sensor (one screw); look for soot/oxide.

Fix: Clean with emery cloth or steel wool.

Shop parts

Common

Failed hot surface igniter

What: Cracked or burned out igniter.

How to check: Watch heat cycle - should glow bright orange in 30s.

Fix: Replace igniter.

Shop parts

Common

Closed gas valve

What: Manual shutoff closed or supply issue.

How to check: Verify shutoff fully open; check other gas appliances.

Fix: Open shutoff or contact gas utility.

Diagnostic Steps

Cut power 60s
Watch heat cycle
Clean flame sensor
Replace igniter if no glow
Verify gas supply

Frequently Asked Questions

How do I fix Rheem code 11?

Most common cause is a dirty flame sensor - clean it with emery cloth. If igniter doesn't glow, replace it.

Same on Ruud?

Yes - identical control system.

Cost to fix?

Flame sensor cleaning: free. Igniter: \$40-80 part.

Related Rheem Codes

Related Symptoms

Need More Help?

Try our interactive symptom diagnostic tool or browse Rheem parts.

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