I have a c7 76 error code. What is my problem?

Remove the bird's nest in the flue.

The 10, 59, 90 and 99 error codes indicate that a Noritz heater has experienced a combustion abnormality. In most cases, it is the result of an obstruction in the heater's flue. Examine the flue to see if it is blocked by debris and clean if necessary.

How To Resolve The Seven Most Common Noritz Tankless ...

Noritz https://www.noritz.com > Blog
Nov 16, 2015 - This error code involves a breakdown in communication between two tankless water heaters using the Quick Connect Cord. It can occur when more ...

Troubleshooting Noritz Tankless Water Heaters and Error Codes

home-water-heater.com https://www.home-water-heater.com > noritz-error-co...
Error code 90 and 99 ... Action: Check for the obstructed venting, improper gas burning (flame shape and color change). Ensure the water heater gets the ...

Error Codes for a Noritz Water Heater - Waterheatertimer.org

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Here is a link to all the Noritz error codes. There is NO Code 67. https://inspectapedia.com/heat/Noritz-NCC199-Error-Codes.pdf

Copy following link for Rheem tankless troubleshoot resources, including error codes, manuals, and general information for maintaining your tankless computer that heats water.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html
Multiple error codes can indicate failed PC board. Rheem will send PC board... so your computer-that-heats-water might have failed motherboard.
Continual maintenance can help avoid common error codes, but some problems are insoluble and chronic.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

1) Copy following links for Rheem tankless error codes
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html
http://waterheatertimer.org/pdf/Tankless-Error-code-13.pdf

2) Maintain water heater as shown in product manual to avoid common error codes.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Error code 36 does not show in Rheem tankless manuals.

Copy following link for general troubleshoot and error codes, and Rheem contact information:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

Error code 36 does not show in any resource, including 2008 service manual, or 2012 product manual.
Check that remote control display is illustrating the correct number.
For example there is error code 35.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Copy following links to narrow down cause for EA error code:
http://waterheatertimer.org/pdf/Bosch_EA_error_code_troubleshooting.pdf
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Before calling service tech, open following links for Rheem troubleshoot resources including rheem chat, error codes, possible maintenance and service manual.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

Error codes are considered start-point for troubleshooting.
Multiple error codes can mean PC board failure.
http://waterheatertimer.org/pdf/Rheem-error-code-C7-76.pdf
http://waterheatertimer.org/pdf/Error-code-13.pdf
http://waterheatertimer.org/pdf/Tankless-maintenance.pdf

Error codes F1 and F2 do not show among common error codes.
Call Bosch 1-800-642-3111

Before calling service technician, open following links for Bosch troubleshoot resources:
Error codes are considered start-point for troubleshoot.
Multiple error codes can indicate PC board failure.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html
http://www.boschhotwater.com/HelpfulResources/TechnicalSupport/BoschAquaStarModels/250SXOTechSupport/Troubleshoot/tabid/569/Default.aspx
http://forms.boschhotwater.com/Home/BoschTechSupportForm/tabid/614/Default.aspx
http://www.boschhotwater.com/HelpfulResources/TechnicalSupport/BoschAquaStarModels/250SXOTechSupport/ServiceBulletins/tabid/573/Default.aspx

Before calling service technician, open following link for Rheem troubleshoot resources including error codes, Rheem chat, and possible manual:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

Error codes are considered start-point for troubleshooting.
Error code C4 13 is bad oxygen sensor, inadequate incoming air supply, or bad venting. Also bad PC board, or internal wiring, or temperature set too high, damaged burner parts.
http://waterheatertimer.org/pdf/Error-code-13.pdf
http://waterheatertimer.org/pdf/Bosch_Ventilating_tight_houses.pdf

Tankless require yearly maintenance to combustion chamber and burner parts.
Prescribed maintenance can correct some of the issues in error code 13.

Before calling service technician, open following link for Rheen troubleshooting resources and possible error code help plus link to Rheem chat:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

Typically, error codes are start-point for troubleshooting.
Error 76 is communication fault with remote control, which can be bad remote, bad wire, bad wiring connection, or bad part inside tankless.
C4 is oxygen sensor problem or bad venting.
More than 1 error code, or mixed error codes can indicate problem such as bad PC board -or- PCB.