I have a gas leak from the control box the leak is at 38%. I have 5 day to figure out how to repair it or replace it. Hoping I can just replace gas and burner supply lines, Or does it need replaced.

The issue of the Paloma tankless water heater displaying error code C7 38 may be caused by several factors, including a problem with the thermistor or temperature sensor, an issue with the gas valve or gas pressure, or a malfunction with the control unit or circuit board. To troubleshoot, try checking the thermistor and temperature sensor, and verifying the proper functioning of the gas valve and gas pressure. If the problem persists, consider seeking professional repair or service.

* Water in any part of the electrical is a hazard to equipment and operators.
* Shut down all equipment to this device.
* Shut down all equipment if the area is flooded.
* Call your hot water vendor for service.
* Call your Gas utility if this is a gas heater.

*** Following is for information only.***
* Water leaks are from external pipe connections or direct tank connections (that may be under fiber insulation wrap.)
* Shut down electrical before servicing equipment.
* Check if breaker tripped out (half way position). Note which breaker is tripped then shut down breaker to cut power to heater control.
* Shut off gas supply if this heater is gas heated.
* Isolate this heater if your using back up or secondary heaters.
* check electrical box and dry out (after isolating and repairing leak.)
* Use a fan to help dry out area.
* Check components for water damage. Burns, Electrical damage. Replace components as needed.
* Pull out components to dry them if still damp.
* Note that due to time constraints, you may need to replace complete control unit and use the wet one as a back up once it's dried out.(say a week in a dry room).
* The Gas Service techs are pretty good at trouble shooting gas fired equipment. Follow their recommendations.
* Note; equipment failures of this type is usually an indication that the whole system needs service. Heater systems are usually set in place and runs with minimal maintenance. Management usually forgets about this till something happens (a leak?) then it's time to do a complete system overhaul. Many just replace the heater (usually after 8-10 years for a gas heater. 3-5 years if it's critical to operation)

Aloha, ukeboy57

Any gas leak is dangerous, call him back!!!!

Maybe the problem is bad faucet cartridge.
Test for crossover:
http://waterheatertimer.org/Crossover.html

Tankless are really made to be thrown away when problems start.
It's like replacing parts on your computer ... for real, when the hard drive crashes and new one is installed, then rarely are problems repaired satisfactorily.
Repair any brand tankless, any problem, permanently, same day, for $385
http://waterheatertimer.org/How-to-install-gas-water-heater.html

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

1) Copy following link for fixing drain valve on 38 gallon gas water heater with plastic drain valve.
http://waterheatertimer.org/How-to-replace-water-heater-drain-valve.html

2) According to serial number, your GE (Rheem) water heater was made in 3rd month of 2007. No service manuals are available from Rheem. Warranty period is probably 6 year. Unit appears to have reliable White Rodgers gas control valve.
http://waterheatertimer.org/How-to-maintain-water-heater.html
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent

3) Add comment and say what you discover.

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

Air intake is probably clogged, so combustion air flow slowed and caused overheating inside combustion chamber.
This tripped FV system and broke TRD, which is a small glass vial located under burner. The spring-activated air baffle snapped closed and shut off air supply, and also tripped FV lockout of gas control.
Remove burner, replace glass vial ordered from Richmond, and clean air intake.
http://waterheatertimer.org/How-to-repair-Rheem-TRD.html
If you have Intellivent gas control, then it can be reset.
Copy following link to identify gas control valve, and download possible service manual:
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent

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

The gas control is leaking gas around the knob?
The gas control needs to be replaced before causing explosion and/or fire.
Gas control has identifying marks on side.

You're probably in for a service call and/or possibly water heater replacement if unit is more that 5-6 years old.
Your water heater plugs into outlet. Check outlet with cheap circuit analyzer to make sure the unit is receiving correct polarity without line interference.
If unit is in the attic, then add more venting to soffit and roof so pilot is not being snuffed out by hot air. If unit is in basement, then open some doors and a window and see if unit needs more air.
Most gas water heaters require yearly cleaning and service.
Clean the combustion parts and tubes.
Clean the air intake.
Have gas company check gas pressure.
Open following link for possible illustrations:
http://waterheatertimer.org/How-to-install-gas-water-heater.html#troubleshoot

The problem can be bad gas control valve, air in gas line, low gas pressure, gas shut off handle not fully parallel with gas line, dirty combustion parts, lack of combustion air, improper venting. Or combination of all things. It's an electronic gizmo, anything can be bad or shorted, and repair may not last long.

Without a trained service technician to ohm-test the parts using correct service manual, then we are guessing at the cause.

Power vent water heater implies that you have side wall venting which must be replaced with another side-wall vented unit -or- it implies rapid reheating of water.

If water heater is more than 6 years old, you might be money ahead by installing a new one from local box store. Avoid the power vent and electronics. Local box store will have passive roof-venting type water heater BUT box store does not sell side-wall power vent. If your power vent goes up through the roof, then box-store variety gas water heater will work. Total cost $350 do-it-yourself for 40 gallon gas.
Or get 40 gallon 240Volt electric for $220 and connect to circuit breaker box. Requires no venting, and is easy to repair for years to come.
Or small 120Volt electric that plugs into outlet to tide you over until gas repairs can be made.
Look for scratch-n-dent models and always offer 10% off.
http://waterheatertimer.org/How-to-install-gas-water-heater.html
Shower uses 5-9 gallons hot water.