Check the seating of the thermostat, which in a housing component. Make sure the thermostat is seated firmly. Replace the thermostat if it's damaged. Your water will run too hot or too cold if the thermostat is broken.
Inspect the water heater igniter. A cracked electrode, loose ground screw or ground wire on the circuit board could cause the igniter to malfunction. Replace the electrode. Tighten the ground screw and ground wire with a Phillips screwdriver.
Examine the pipes inside the water heater. Replace any leaky pipes.
Look for possible electrical problems. If your water heater runs on electricity, make sure your camper is plugged into the campsite's electrical outlets.