ErrorCodePro · Appliance Error CodesRheem Tankless Water Heater Error Codes: Full List & Meanings
Every Rheem tankless water heater error code we have verified against Rheem's own support pages, with its official meaning. This list covers rtgh high-efficiency non-condensing tankless gas water heaters (use and care manual). Codes vary by model, so confirm in your owner's manual. Support: Rheem tankless support, 1-866-720-2076.
Smell gas? Leave the building now. Do not touch light switches, phones or appliances inside. Call your gas utility or 911 from outside. CO alarm sounding or headache, dizziness or nausea? Get everyone outside and call 911. Gas valves, burners, venting and wiring are for a licensed technician only. See our safety policy.
Codes by system
Heating
Water fill
All Rheem tankless water heater error codes
Codes marked "Reset only" or "Service" have no separate page because the manufacturer publishes no owner fix beyond a reset or a service call.
| Code | Official meaning | System | Owner action |
|---|---|---|---|
| 11 | The gas shut-off valve isn't fully open, so the burner can't light. | Heating | Owner checks |
| 12 | Gas service has been interrupted, or on LP models the propane supply is running low. | Heating | Owner checks |
| P1 | There isn't enough water flow to run the unit. | Water fill | Owner checks |
| 1L | Lime (scale) buildup in the water heater: contact a dealer or qualified service technician. | Control / electronics | Service |
| 14 | Water heater overheating: contact a dealer or qualified service technician. | Control / electronics | Service |
| 31 | Faulty inlet thermistor: contact a dealer or qualified service technician. | Control / electronics | Service |
| 33 | Faulty outlet thermistor: contact a dealer or qualified service technician. | Control / electronics | Service |
| 61 | Faulty blower motor: contact a dealer or qualified service technician. | Control / electronics | Service |
| 66 | Faulty bypass motor: contact a dealer or qualified service technician. | Control / electronics | Service |
| 88 | Reminder to flush the heat exchanger and/or replace the water treatment filter: contact a dealer or qualified service technician. | Status / reminder | Service |
Symptoms
Sources
Last reviewed: October 20, 2026. ErrorCodePro is not affiliated with Rheem.