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Rheem Tankless Water Heater Error Codes: Performance Plus and Prestige Series Guide

Quick Answer

Rheem tankless water heater error codes: P1 = low gas pressure, P2 = ignition failure, E5 = overheating, C7 = flame sensor fault. Find your code in the list below. Most Rheem codes require checking gas supply, venting, or the heat exchanger for scale. Annual descaling extends unit life significantly.

Rheem tankless water heater error codes appear on the built-in LCD display. To access stored error codes, press and hold the Up and Down buttons simultaneously for 3 seconds to enter diagnostic mode. The most common code is Code 11 (ignition failure), which means the burner failed to light after multiple attempts. Other codes include Code 12 (flame sensor signal lost), Code 13 (exhaust fault), and Code 76 (communication error). Code 11 is usually resolved by cleaning the flame rod or checking gas supply.

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About These Rheem Waterheater Error Codes

Rheem tankless water heater error codes display on the LCD. Code 11 (ignition failure) is the most common. Enter diagnostic mode by holding Up + Down buttons for 3 seconds.

Most Common Error Codes

Ignition lockout from failed or dirty ignitor40%

Flame sensor not detecting pilot or burner flame24%

Air/exhaust venting blockage triggering safety shutdown14%

Gas pressure below minimum spec (3.5 inches w.c.)12%

Scale buildup in heat exchanger restricting flow10%

Symptoms You May Notice

No hot water output
Error code displayed on LCD panel
Unit attempts to fire then shuts off
Hot water is cold or lukewarm only
Unit clicks multiple times then displays a code

Frequently Asked Questions

How do I read error codes on a Rheem tankless water heater?

Error codes display automatically on the LCD when a fault occurs. To access stored error history, press and hold the Up and Down arrow buttons simultaneously for 3 seconds to enter diagnostic mode. Codes will cycle through the display.

What is the most common error code on a Rheem tankless water heater?

Code 11 (ignition failure) is the most common Rheem tankless error. It means the unit attempted to light the burner and failed. The most frequent cause is a dirty flame rod, though gas supply issues and igniter failures also trigger Code 11.

Can I reset a Rheem tankless water heater error code myself?

Yes. After addressing the underlying issue, press the Reset button on the unit (or hold the power button for 5 seconds on some models) to clear the error and attempt restart. Do not repeatedly reset without addressing the root cause as some faults can damage the unit.

Are Rheem error codes the same as Rinnai or Noritz codes?

Code numbers are sometimes the same across brands but meanings can differ. Code 11 happens to mean ignition failure across Rheem, Rinnai, and Noritz. However, other codes differ significantly. Always look up the code for your specific brand.

Does Rheem offer a warranty on tankless water heater repairs?

Rheem Performance Plus and Prestige series tankless units typically carry a 12-year heat exchanger warranty and a 5-year parts warranty when registered. Warranty service must be performed by a licensed plumber.

Related Rheem Waterheater Error Codes

Code: 11Rheem Tankless Water Heater Code 11: Ignition Failure Fix

Same Fix on Other Brands

Rinnai waterheater11: Rinnai Code 11: No Ignition Noritz waterheater11: Noritz Code 11: No Ignition

Models Known to Experience HUB Errors

This repair applies to most Rheem waterheaters with this error code. Common model numbers include:

RTGH-95DVLN, RTGH-84DVLN, RTG-95XLN

Last verified for technical accuracy on March 14, 2026