Why does my eternal tankless water heater code E03 mean?

SOURCE: No hot water from tankless water heater. Bliniking Readout

http://www.rheemtankless.com/content/tankless/rheem/help.shtml

This is there website.Above.
Use the live chat to ask them, the code you listed does not seem to correspond to there code list, the only code that does is code 76,
which is a problem with the remote control not talking to the unit.
So your best bet is to tell them the error.

SOURCE: Paloma PTG 74PVN Tankless Water Heater

did you check the filters on the the water valves, i am not exactly sure about your codes that are shoeing but if you could read it and post them, i know on some of the units 76 means there is low water pressure and the filters are behind 2 caps one on each side above the shut off valve take off the caps and remove the screens, clean them and replace them ,, make sure you turn off the water on both side first or you will get wet

SOURCE: Paloma tankless, gas, water heater, error code C7 76

If you look on the left hand side of the burner control module you'll see 4 capacitors - the capacitors have most likely failed...pretty sure anything code 76 is P/S failure. It may also be covered for manufactures defects. If the cap is blown..the top will be slightly raised as apposed to flat like the other nearby caps - they are called top blow capacitors...the damage should be evident.

SOURCE: what does C2 11 error code mean on my Paloma

I had the same problem with my Paloma a year and a half after installation...contacted Rheem customer service (800-432-8373) and they recommened a local installer in my area. However, if you're fairly capable, they will email you a step-by-step process on how to solve the problem yourself. They'll provide assistance through the process over the phone as well.

SOURCE: what is trouble code C8 on a rheem tankless water

c8 is a cycle not a code... the code comes up after it, may look like a temperature... 2 digiti numbetr