# Rheem tankless gas water heaters error codes | Costolio URL: https://costolio.com/home/appliances/rheem/rheem-tankless-gas-water-heaters/ Updated: 2026-11-02 # Rheem tankless gas water heaters error codes 10 water heater error codes for Rheem tankless gas water heaters, what each one means and what to try, paraphrased from Rheem's own source. Codes vary by model, so confirm in your own manual. Safety. The manual warns that diagnosing this heater can expose you to electric shock and gas; turn off all power before replacing parts and get a licensed, qualified professional. Source: [Tankless Gas Troubleshooting Pocket Manual SVC820 (P) (Rheem)](https://files.myrheem.com/webpartners/ProductDocuments/B2700906-82CE-41D7-B104-3B8A3B9E690A.pdf). ## All codes - [P1](https://costolio.com#p1) Not enough water flow. - [1L](https://costolio.com#1l) Lime build-up detected in the heat exchanger. - [05](https://costolio.com#05) Improper burner combustion (indoor units). - [11](https://costolio.com#11) No flame detected, usually gas supply or venting. - [12](https://costolio.com#12) Flame was detected and then lost, usually gas supply or venting. - [14](https://costolio.com#14) The over heat limiter has opened. - [16](https://costolio.com#16) Outlet water is hotter than the set point. - [29](https://costolio.com#29) Condensation is not draining. - [61](https://costolio.com#61) The blower speed is wrong for proper combustion. - [71](https://costolio.com#71) The gas control valve (inlet solenoid) has malfunctioned. ## P1 What it means: Not enough water flow. You can usually fix this yourself. ### What to try - Turn the water supply to the unit off, turn the remote control off, wait 10 seconds and turn it back on, then turn the water supply on and check the nearest hot water fixture for hot water. - Make sure the hot and cold water supply lines are not crossed. ## 1L What it means: Lime build-up detected in the heat exchanger. This one often needs a licensed technician. ### What to try - The unit must be drained and flushed. - Reset by holding MIN and MAX together for 10 seconds. ## 05 What it means: Improper burner combustion (indoor units). This one often needs a licensed technician. ### What to try - Have a licensed technician check the gas supply and venting. ## 11 What it means: No flame detected, usually gas supply or venting. This one often needs a licensed technician. ### What to try - Have a licensed technician check gas supply, venting, igniter and flame rod. ## 12 What it means: Flame was detected and then lost, usually gas supply or venting. This one often needs a licensed technician. ### What to try - Have a licensed technician check gas supply, venting and flame rod. ## 14 What it means: The over heat limiter has opened. This one often needs a licensed technician. ### What to try - Have a licensed technician check the gas supply and venting. ## 16 What it means: Outlet water is hotter than the set point. This one often needs a licensed technician. ### What to try - Have a technician check the outlet thermistor first, then the bypass valve. ## 29 What it means: Condensation is not draining. You can usually fix this yourself. ### What to try - Have a licensed technician check that the condensate drain is not blocked. ## 61 What it means: The blower speed is wrong for proper combustion. This one often needs a licensed technician. ### What to try - Have a technician check the blower motor. ## 71 What it means: The gas control valve (inlet solenoid) has malfunctioned. This one often needs a licensed technician. ### What to try - Have a licensed technician check the gas control valve. ### Source - [Tankless Gas Troubleshooting Pocket Manual SVC820 (P) (Rheem)](https://files.myrheem.com/webpartners/ProductDocuments/B2700906-82CE-41D7-B104-3B8A3B9E690A.pdf) (checked 2026-11-02) Brand names and model names are trademarks of their owners. Costolio is not affiliated with or endorsed by any manufacturer. ## Related - [A.O. Smith residential standard gas water heaters error codes](https://costolio.com/home/appliances/a-o-smith/a-o-smith-residential-standard-gas-water-heaters/) - [Bradford White water heaters error codes](https://costolio.com/home/appliances/bradford-white/bradford-white-water-heaters/) - [All appliance error codes](https://costolio.com/home/appliances/)