Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater 33 Error Fix: Incoming Water Temperature Sensor Failure

The thermistor at the cold water inlet is reading out of range, has an open circuit, or is shorted. This sensor measures the incoming cold water temperature so the control board can calculate the required BTU output — the board needs to know the temperature differential between incoming and desired outgoing water to determine the correct burner firing rate. A failed inlet sensor causes incorrect heat modulation or complete shutdown. Replace the inlet water temperature sensor. Same diagnostic procedure as Code 32.

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Quick Answer

Error 33 on the Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater means: Incoming Water Temperature Sensor Failure. The top-ranked community fix is “Test and Replace Inlet Water Temperature Sensor” (medium difficulty, ~45 min, DIY cost: $15-$25). 2 community-ranked fixes available below.

Published February 2026 · 2 fixes · water heater

Content is based on manufacturer service documentation, community repair experience, and OEM technical bulletins. Always verify with your owner's manual.Learn about our editorial standards.

When to Call a Professional

While many water heater repairs can be done safely at home, consider hiring a qualified technician if:

The repair involves electrical wiring, gas lines, or refrigerant
You've tried the top-ranked fix and the error persists
You smell gas, see sparking, or notice water leaking
The repair requires specialized tools you don't have
Your appliance is still under manufacturer warranty

Average professional repair cost for this issue: $120-$180.

Other Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater Error Codes

False Flame Detection

2 fixes

Abnormal Combustion — Blocked Vent

2 fixes

Ignition Failure — No Flame Detected

2 fixes

Flame Failure — Flame Lost During Operation

2 fixes

Thermal Fuse Activated — Overheat Safety

2 fixes

Overheating — Outgoing Water Too Hot

2 fixes

Abnormal Temperature Rise — Low Water Flow

2 fixes

Condensate Drain / Vent Blockage

2 fixes

People Also Ask About Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater Error 33

What does error code 33 mean on a Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater?

Error code 33 on the Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater means: Incoming Water Temperature Sensor Failure. The thermistor at the cold water inlet is reading out of range, has an open circuit, or is shorted. This sensor measures the incoming cold water temperature so the control board can calculate the required BTU output — the board needs to know the temperature differential between incoming and desired outgoing water to determine the correct burner firing rate. A failed inlet sensor causes incorrect heat modulation or complete shutdown. Replace the inlet water temperature sensor. Same diagnostic procedure as Code 32.

How do I fix error code 33 on my Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater?

The most successful fix is "Test and Replace Inlet Water Temperature Sensor" (medium difficulty, ~45 minutes). Estimated DIY cost: $15-$25. HomeMD has 2 community-ranked fixes for this error.

Is error code 33 on a Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater serious?

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

Can I fix Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater error 33 myself?

Yes — the top-ranked community fix ("Test and Replace Inlet Water Temperature Sensor") is rated medium difficulty and takes about 45 minutes. Tools needed: T20 Torx screwdriver, Digital multimeter.

How much does it cost to repair Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater error 33?

DIY cost: $15-$25. Professional repair typically costs $120-$180. Many homeowners save money by trying the top-ranked community fix first.

What other error codes does the Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater have?

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.

What other error codes does the Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater have?

The Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater has 8 other known error codes:

05 — False Flame Detection (2 fixes)
10 — Abnormal Combustion — Blocked Vent (2 fixes)
11 — Ignition Failure — No Flame Detected (2 fixes)
12 — Flame Failure — Flame Lost During Operation (2 fixes)
14 — Thermal Fuse Activated — Overheat Safety (2 fixes)
16 — Overheating — Outgoing Water Too Hot (2 fixes)
24 — Abnormal Temperature Rise — Low Water Flow (2 fixes)
29 — Condensate Drain / Vent Blockage (2 fixes)

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