Error code 13, replace burner and vent kit, still getting error code Rheem tankless hot water heater

Before calling service technician, open following link for troubleshoot resources:
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

The same error code and problem on one person's tankless unit can have different solution than another tankless unit.
This is because tankless require perfect operation of parts and sensors while being affected by incomming water and gas issues, and venting, plus plumbing factors.
Replacing one part is not always the fix, since that part interrelates with so many other parts, each affected by the operation of the other, and operation of the chip and integrity of wiring and wiring connections.

Read manual for yearly maintenance requirements, and calculate those costs when figuring anticipated $1-8 monthly energy savings from owning tankless.
Check that your region has reasonably-priced, qualified service technician for your brand before buying tankless. And check part list and cost of parts before buying any water heater because these factors weigh-in after a few years of operation.

Repair most tankless problems yourself, same day, any brand, for around $330.
http://waterheatertimer.org/How-to-install-gas-water-heater.html

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