What do Rheem and Ruud furnace error codes mean?
Rheem and Ruud 801T furnaces flash codes such as 11 failed ignition, 22 limit open and 33 rollout open, per Rheem's installation instructions. Codes 55 and 57 are pressure switch faults. Your door chart wins if it differs.
Key points
- Newer Rheem and Ruud single-stage furnaces show two-digit codes on a seven-segment display; the first digit shows for one second, then the second.
- The table below comes from Rheem's (-)801T installation instructions (form 92-24161-144), which Ruud's R801T furnaces share by model family.
- Other series, two-stage models and older boards use different codes. The chart on your furnace door or in your own manual wins.
- Read the display without removing panels, write the code down, check the thermostat, filter and vents, then call if it returns.
- Limit, rollout and unexpected-flame codes are stop-and-call faults, not resets.
On a Rheem or Ruud 801T furnace, the LED shows a two-digit code one digit at a time, and the table below, taken from Rheem's installation instructions for its (-)801T single-stage furnaces, says what each code means. Your furnace may use a different chart, so the one on the furnace door or in its own manual is the final word. The display repeats after a pause, so watch a full cycle.
Do Rheem and Ruud furnaces share error code charts?
For the 801T family, yes. Ruud publishes an R801T upflow/horizontal furnace spec sheet that lists a seven-segment LED diagnostic display on every unit, and the same sheet says Ruud trademarks are owned by Rheem Manufacturing Company. Rheem's installation instructions (form 92-24161-144, Rev. 12) cover the "(-)801T" series, with the brand letter left as a placeholder. A Ruud-branded R801T downflow manual uses the same prefix.
Codes can differ by control board and series, so a two-stage or older Rheem model may not read the same way. If your furnace is not an 801T-family model, treat the table as an example of how these displays work, not as your answer.
How to read the display safely
- Leave the furnace as it is. Look at the display through the door window if your model has one. Don't remove panels or reach into the burner or blower compartment while the furnace has power.
- Watch a full cycle. The manual says each two-digit fault shows the first digit for one second, then the second digit for one second, then a pause, and repeats. A fault is shown at least twice, even if it clears first.
- Write down the code, plus any letter. A steady letter is not a fault: H means gas heat is on, C is compressor on, F is continuous fan, and 0 is standby.
- Photograph the rating plate. The model number tells a technician which chart applies.
- Do this before anyone cycles the power. Cutting power can clear the very code you came to read.
Rheem (-)801T fault codes
Codes from Rheem's (-)801T upflow/horizontal installation instructions:
| Code | Meaning in the manual |
|---|---|
| 10 | One-hour lockout |
| 11 | Failed ignition |
| 12 | Low flame sense |
| 13 | Flame lost |
| 14 | Unexpected flame |
| 20 | Twinning fault |
| 22 | Main limit or HALC open |
| 26 | Line and neutral reversed |
| 33 | MRLC (manual reset limit control, also called roll-out) open |
| 55 | Pressure switch stuck closed when it should be open |
| 57 | Pressure switch stuck open when it should be closed |
| 61 | Blower fault, blower unable to run |
| 93 | Internal control fault |
Two codes can alternate. After four failed ignitions in a row, the manual says the control enters a one-hour lockout and shows 10 and 11 in turn. After flame is lost five times in a row, it shows 10 and 13.
What the common code families mean
Ignition and flame (11, 12, 13). The burners didn't light, or lit and couldn't prove flame. Causes run from the gas supply and a weak ignitor to a dirty flame sensor. Our flame sensor post covers the last one.
Pressure switch (55, 57). The furnace uses the switch to prove the inducer is venting exhaust. In a Minnesota winter, the usual causes are frost or snow over the PVC vents, a frozen condensate trap or a failing inducer. See the furnace pressure switch guide.
Limit (22). The furnace got too hot. That points to airflow: a clogged filter, closed registers or a failing blower. Read what a limit switch does.
Rollout (33). Flame went where it shouldn't. The manual calls it a manual-reset control, which tells you it isn't a repeat-reset item.
Unexpected flame (14) and internal fault (93). Both are technician jobs. The manual says a 93 lockout can't be cleared by cycling the heat call.
Safe checks and when to call
Before you call, run the basic checks in our general furnace light codes guide: thermostat, furnace switch and breaker, filter, snow on the PVC vents and water at the furnace. Cycle the power once, and if the same Rheem code comes back, stop. Never bypass or jumper a pressure, limit or rollout switch, and never reset the furnace over and over to keep it running. A gas smell means leave the house and call the gas utility or 911 from outside.
When you call, give us the two digits in order, whether 10 is alternating with 11 or 13, any steady letter on the display and the model number from the rating plate. The alternating pair tells us whether the control locked out after failed ignitions or after repeated flame loss, which points the visit at different parts. Call us if the code returns after one reset, or if it's a limit (22), rollout (33), unexpected-flame (14) or internal (93) fault. We read the code, check the stored fault history where the board keeps one, then test the part the code points to rather than replacing it on a guess. Our furnace repair is a $79 trip charge, waived when you approve the repair, with a written flat-rate price before work starts. See our page on furnace repair in Minneapolis for how a visit works. We're open 7 days, 7am–9pm: ring 612-429-3465 and have the code and the model number from the rating plate ready.
Common questions about heating
What does code 11 mean on a Rheem furnace?
On the 801T chart, 11 is failed ignition: the burners did not light or the flame was not proven. After four failed tries in a row the control goes into a one-hour lockout and alternates 10 and 11. Check the thermostat, furnace switch and gas supply at the appliance valve, then call if it repeats.
Can I reset a Rheem furnace to clear a code?
Rheem's manual says soft lockouts clear when power is cycled off and on or the heat call is cycled. Do that once, after the simple checks. If the same code returns, the cause is still there and repeated resets will not fix it. Call us instead of resetting again.
What if my Rheem or Ruud furnace has no display, only a blinking light?
Older and some other models use a blinking LED instead of a two-digit display, with a different chart that varies by board, so it is not listed here. Count the flashes, then match them to the label on the furnace door or call us with the model number.
Does a Rheem furnace code clear by itself?
Sometimes. Codes for a failed ignition, lost flame or open limit can clear after the furnace cools or a retry succeeds, but the control stores the fault and repeats it if the cause remains. A one-hour lockout, shown as 10 and 11 alternating, resets itself after the hour. If the same code returns after one power cycle, stop and call.
Sources
- Rheem manufacturer documentation rheem.com