Rheem Error Code 26: Line and neutral reversed (Furnace)

Updated October 13, 2026 · by Aurora Star Tech Inc.

Rheem error code 26 on a furnace means: Line and neutral reversed. It is also called Rheem diagnostic code 26.

High severityFurnaceRheem/Ruud 802P / 80MDP 80% two-stage furnace (UT 1028-928 IFC) · R95P · RGPE/RGLE

Homeowner? What Rheem code 26 means for you

Call a technician Your furnace is reporting: Line and neutral reversed. The furnace has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.

Safe things you can check yourself

Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
Make sure the unit has power: its on/off switch (often looks like a light switch near the unit) is ON and the breaker in the electrical panel is not tripped.
Make sure the furnace front door or panel is closed properly; many furnaces will not run with the door switch open.
Look at the air filter. If it is grey and clogged, replace it; a blocked filter causes many shutdowns.
Outside, make sure the intake and exhaust pipes or vent cap are not blocked by snow, ice, leaves or a nest.
Check that the gas valve next to the furnace is open (handle in line with the pipe). Do not force it.
Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.

Call (647) 657-2977 Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does Rheem error code 26 mean?

Supply polarity is reversed. The control may not sense flame when L1 and neutral are swapped; RGPE/RGLE will not operate without correct polarity and also alerts the homeowner (Call For Service).

Applies to: 802P/80MDP (802PA050-150); R95P (R95PA040-115); RGPE/RGLE 2-stage 80+

Common causes of Rheem code 26

L1 (hot) and neutral swapped at the junction box or IFC
Poor or missing ground

Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.

Rheem models that use code 26

Show all 21 models

R95PA0401317MSA R95PA0601317MSA R95PA0701317MSA R95PA0851521MSA R95PA1001521MSA R95PA1151524MSA R802PA050314MSA R802PA075417MSA R802PA100521MSA R802PA125524MSA R802PA150524MSA RGLE-05(-)BMKR RGLE-07(-)AMKR RGLE-07(-)BRQR RGLE-10(-)BRMR RGLE-12(-)ARMR RGPE-05(-)BMKR RGPE-07(-)AMKR RGPE-07(-)BRQR RGPE-10(-)BRMR RGPE-12(-)ARMR

Other Rheem Furnace codes

Code	Meaning
12	Low flame sense
13	Flame lost
14	Unexpected flame
20	Twinning fault
22	Main limit open
23	HALC limit open (HALC LIMIT OPEN)
33	Rollout switch (MRLC) open
44	Low pressure switch closed (stuck)
45	Low pressure switch open - inducer high speed
46	Low pressure switch open - inducer low speed
55	Pressure switch stuck closed
57	Pressure switch stuck open

All Rheem Furnace error codes →

Rheem code 26: homeowner questions

What does Rheem code 26 mean?

Line and neutral reversed. Supply polarity is reversed. The control may not sense flame when L1 and neutral are swapped; RGPE/RGLE will not operate without correct polarity and also alerts the homeowner (Call For Service).

Is it safe to keep using my furnace with code 26?

It depends on the cause. The furnace has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.

Can I reset Rheem code 26 myself?

You can try one reset (power off for 30 seconds, then on). If Rheem code 26 comes back, the cause is still there and a licensed technician should check it.

Who can fix Rheem code 26 near me?

Aurora Star Tech Inc. repairs Rheem furnaces in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.

Homeowner help: Furnace Not Turning On: What to Check · Furnace Blinking Light: What the Flash Codes Mean

Troubleshooting guides

Blowing cold air All brands · Furnace
No heat All brands · Furnace
Short cycling All brands · Furnace
Blower does not start after burners light Rheem · Furnace
Burners go out before the heat call ends / short cycling Rheem · Furnace
Communicating system not found / no communication Rheem · Furnace
ECM blower does not start on heat Rheem · Furnace
Furnace no heat - sequence troubleshooting Rheem · Furnace
Furnace short cycles or does not hold setpoint Rheem · Furnace
Gas valve does not shut off when heat call ends Rheem · Furnace
Indoor blower does not start after burners light Rheem · Furnace
Inducer (draft motor) does not start on heat call Rheem · Furnace
Inducer does not run / does not run on low speed Rheem · Furnace
Inducer runs 60 s then shuts off for 5 minutes, or runs continuously Rheem · Furnace
Inducer runs 60 seconds then off for 5 minutes Rheem · Furnace
No heat - inducer (IDM) does not start Rheem · Furnace
No heat - POWER LED off Rheem · Furnace
Read target airflow from the CFM LED Rheem · Furnace
Thermostat does not hold room temperature Rheem · Furnace

Source: 802P: 92-24161-146-02, Diagnostics and Fault Codes table, p.28, 40; R95P: Diagnostics and Fault Codes table, p.87 (PDF p.91); RGPE/RGLE: Table 16 p.49 / Table 20; Electrical Checks p.24. Written in our own words as a summary; always check the original manual.

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.