HeatingCodesRheem and Ruud furnace display alternating 10 and 11: one-hour lockout after failed ignition
What 10 and 11 mean together
Rheem's installation instructions for the (-)801T series list code 10 as a one-hour lockout and code 11 as failed ignition. When a failed ignition has occurred four times in a row, the control enters a one-hour lockout and displays 10 and 11 alternately. Code 10 on its own tells you only that the furnace is in a soft lockout. The second code tells you what caused it.
Each two-digit code is shown one digit at a time. The first digit appears for one second, then the second digit for one second, then a half-second pause, and then the cycle repeats. So 1 then 0 is code 10, and 1 then 1 is code 11.
All the situations that cause a "10" lockout
Rheem says a one-hour soft lockout starts when any of these happens, and the display alternates 10 with the code for the cause:
| Display alternates | Cause (per Rheem) |
|---|---|
| 10 and 11 | Flame has not been detected after four ignition trials. |
| 10 and 13 | Flame was lost five times in one heat call. |
| 14 and 10 | Undesired (unexpected) flame was detected. The hour starts after flame is no longer detected. |
| 61 and 10 | A dead blower was detected: the main limit circuit was open for more than 150 seconds. |
| 10 and another code | Voltage was unexpectedly detected on the gas valve circuit and went away when the inducer shut off. |
How a lockout resets
Rheem says all lockout conditions can be cleared immediately once the original fault is cleared and power to the unit is cycled off and back on. For a soft lockout only, the lockout can also be cleared if the heat call is cycled off for more than 2 seconds but less than 20 seconds. Otherwise the soft lockout resets automatically after one hour. The control will not start a heat cycle during any lockout.
Rheem's document does not list the physical causes of a failed ignition in this section. Other manufacturers' manuals list the usual suspects: no gas, a weak igniter, a dirty or coated flame sensor, a pressure switch problem and blocked venting. For comparison, see Goodman EE0 and Lennox E270, which describe the same situation on different controls. Finding the cause on a Rheem furnace is technician work.
Safe homeowner checks for Rheem or Ruud furnace codes 10 and 11
- Check that gas is availableSee whether another gas appliance such as a stove or water heater is working. If you smell gas, leave the house and call your gas utility from outside.
- Clear outdoor vent and intake pipesFrom the ground, clear snow, ice or debris from the plastic vent and combustion air terminations. Do not climb on a roof or take pipes apart.
- Reset once with the thermostatSet the thermostat below room temperature for about 10 seconds (more than 2, less than 20), then back to heat. This is the soft-lockout reset Rheem describes.
- Stop if it returnsIf the display goes back to 10 and 11, turn the thermostat off and call a heating technician. Repeated attempts will not fix a gas, igniter or flame sensing problem.
Frequently asked questions
How long does the Rheem furnace stay locked out?
One hour for a soft lockout. It resets automatically after that, or sooner if you cycle power or end the heat call for more than 2 and less than 20 seconds.
What does 12 mean on a Rheem furnace?
Rheem lists code 12 as low flame sense, which is the control reporting a weak flame signal. It is separate from 11 (failed ignition) and 13 (flame lost).
What is a hard lockout on this furnace?
Rheem describes it as code 93 (internal control fault) or a dead blower declared four times in one heat call (code 61). A 93 hard lockout cannot be reset by cycling the heat call.
Sources
- Installation Instructions 92-24161-144-08: Upflow/Horizontal Single Stage Gas Furnaces, (-)801T and (-)(-)80MSX series, section 14 Diagnostics and Fault Codes (Rheem (Rheem and Ruud brands)) Covers: Rheem and Ruud (-)801T upflow/horizontal single-stage furnaces and (-)(-)80MSX upflow/horizontal furnaces with the seven-segment display control. Other Rheem and Ruud furnace series can use different controls.
Safety note: this page is general information drawn from the sources above. Gas, combustion and line-voltage repairs belong to a licensed professional. Your own equipment's label and manual take priority over anything here. Read the full disclaimer.