Most gas water heater problems today can be solved with yearly maintenance that includes cleaning burner parts, clean air intake, check venting, check electrical connections, bleed gas line, and check gas pressure.
Gas water heater manuals recommend yearly maintenance by service technician.
In past years, gas water heaters required less maintenance, but they were less energy efficient and more dangerous to operate.
Sounds like you have Intellivent gas control valve thermostat.
Open following link to identify gas valve and see error codes:http://waterheatertimer.org/pdf/Intelli-vent-gas-valve2.pdfhttp://waterheatertimer.org/How-to-adjust-temperature-on-water-heater.html#intelli
Error light on vacation + 2 other lights = 3 possible conditions:
1) Wiring error: check outlet with circuit analyzer:http://waterheatertimer.org/images/Typical-circuit-analyzer-15.jpg
2) Pressure switch tubing not connected, air intake obstructed (clean intake), or vent exhaust obstructed (check for proper venting).http://waterheatertimer.org/images/Test-water-heater-vent-400.jpg
3) System in lockout: Low gas pressure, hot surface igniter not positioned correctly.
You can do some of this yourself.