I'm needing some advice on my tankless. It's been running beautifully for about 16 months but in the past couple of days has stopped heating a few minutes into use.

The front error lamp just flashes repeatedly with no pattern. If I recycle the power on it, it'll start up and give me hot water again but then shut down as before.

I didn't get one of the fancy remote control things so don't have a code to go by.

Any troubleshooting advice?

Thanks very much.