RINNAI E110CN Low Output Temp

[rbrookecoleman]

Hi. Couldn't find this anywhere. My Rinnai e110CN intermittently and now permanently acting like it's 40F outside. It seems to be stuck in efficient mode with water temp at 115-120F instead of 165F. It's about 8F outside. The result is temp dropping in house. It did this a few times and it corrected when I pressed boiler on/off button (off then back on). It doesn't return to full flame when I disconnect outside temp sensor either. Burner is firing - just not hard. Feels like it must be a sensor giving it bad info. Thoughts? Thx in advance.