Rheem Error Code 6 blinks: Line and neutral reversed (Furnace)

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

Rheem error code 6 blinks on a furnace means: Line and neutral reversed. It is also called Rheem diagnostic code 6 blinks.

Medium severityFurnaceRheem RGRM/RGTM 90 Plus

Homeowner? What Rheem code 6 blinks means for you

Check, then call Your furnace is reporting: Line and neutral reversed. This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.

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 6 blinks mean?

The STATUS LED on the furnace control flashes 6 times: the control sees hot (L1) and neutral swapped on the 115 V supply. With reversed polarity the control may not be able to prove flame, so the furnace can light and drop out or lock out.

Applies to: Rheem RGRM upflow and RGTM downflow/horizontal two-stage condensing gas furnaces (90 Plus)

Common causes of Rheem code 6 blinks

L1 (hot) and neutral swapped at the furnace junction box or in the supply wiring
Wrong polarity at a receptacle or plug-in cord feeding the furnace
Poor or missing ground at the furnace or control

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 6 blinks

RGRM-04 RGRM-06 RGRM-07 RGRM-09 RGRM-10 RGRM-12 RGTM-06 RGTM-07 RGTM-09 RGTM-10

Other Rheem Furnace codes

Code	Meaning
1 blink	Soft lockout (failed ignition)
2 blinks	Pressure switch circuit open
3 blinks	Limit circuit open
4 blinks	Pressure switch circuit closed (stuck closed)
5 blinks	Twinning fault (optional)
10	One-hour lockout
11	Failed ignition
12	Low flame sense
13	Flame lost
14	Unexpected flame
20	Twinning fault
22	Main limit open

All Rheem Furnace error codes →

Rheem code 6 blinks: homeowner questions

What does Rheem code 6 blinks mean?

Line and neutral reversed. The STATUS LED on the furnace control flashes 6 times: the control sees hot (L1) and neutral swapped on the 115 V supply. With reversed polarity the control may not be able to prove flame, so the furnace can light and drop out or lock out.

Is it safe to keep using my furnace with code 6 blinks?

It depends on the cause. This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.

Can I reset Rheem code 6 blinks myself?

You can try one reset (power off for 30 seconds, then on). If Rheem code 6 blinks comes back, the cause is still there and a licensed technician should check it.

Who can fix Rheem code 6 blinks 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

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Source: Rheem RGRM/RGTM Installation Instructions 92-24161-84-01 (Nature Air RGRM-04*MAES on ManualsLib), Troubleshooting - STATUS LED codes, p.53; Electrical Wiring polarity note. 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.