HIGH URGENCY

Rheem Code 26 - Reversed Polarity

Code 26

Line voltage polarity reversed - wiring fault.

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

What This Code Means

Code 26 on Rheem (Ruud) means the incoming 115VAC line voltage has reversed polarity. Hot and neutral are swapped, or there is a grounding issue.

Most common

What: Wires swapped at disconnect or in home wiring.

How to check: Electrician tests outlet/wiring polarity.

Fix: Correct wiring.

Common

What: Improper or missing ground connection.

How to check: Electrician verifies ground.

Fix: Restore proper ground.

Less common

What: Board incorrectly reads polarity.

How to check: Tech diagnostic.

Fix: Replace board.

Shop parts

Is Rheem code 26 dangerous?

Yes - it indicates an electrical wiring problem. Have a licensed electrician check before operating.

Will it damage my furnace?

Can damage control board over time.

Same on Ruud?

Yes.