Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater 16 Error Fix: Overheating — Outgoing Water Too Hot

Error code 16 on the Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater means: Overheating — Outgoing Water Too Hot. The outlet water temperature has exceeded the maximum safe limit (typically above 185°F / 85°C). The unit shuts down to prevent scalding. The most common cause is scale (calcium/mineral) buildup inside the heat exchanger tubes — as scale narrows the internal passages, water moves through more slowly and absorbs excessive heat. Descale the heat exchanger using a tankless water heater descaling pump kit with white vinegar or a commercial descaling solution (circulate for 45-60 minutes). Other causes: a failed outlet thermistor reading lower than actual temperature (causing the unit to fire harder than needed), or a stuck-open modulating gas valve. After descaling, if the code persists, check the outlet thermistor (see Code 32).

The most successful fix is "Test and Replace the Outlet Thermistor" (medium difficulty, ~45 minutes). Estimated DIY cost: $5-$20. HomeMD has 2 community-ranked fixes for this error.

This error is rated critical severity. It is generally not urgent and can often be resolved with a simple DIY fix.

Yes — the top-ranked community fix ("Test and Replace the Outlet Thermistor") is rated medium difficulty and takes about 45 minutes. Tools needed: T20 Torx screwdriver, Multimeter, Needle-nose pliers.

DIY cost: $5-$20. Professional repair typically costs $120-$180. Many homeowners save money by trying the top-ranked community fix first.

The Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater has 8 other known error codes, including: 05 (False Flame Detection), 10 (Abnormal Combustion — Blocked Vent), 11 (Ignition Failure — No Flame Detected), 12 (Flame Failure — Flame Lost During Operation), 14 (Thermal Fuse Activated — Overheat Safety), and 3 more.