The only error codes are E1, E2, and E3. If the digital display on the control panel reads L1, L2, L3 or L4, etc. this is not an error, it is the flame setting, and will disappear after a few seconds.
Though both flame lights and heat use the digital display to communicate, they function separately from one another. This means that if the control panel reads L4 and there is no heat, the unit is set to a bright flame with the heat off. To add heat to your flame setting press the heater button (three wavy lines), and then the increase decrease button (up/down arrows) to cycle to your preferred temperature.
For photos and an explanation of the different digital display readings on the fireplace insert, click here.