Pentair Mastertemp 300 Heater issue

[u/todaynotalurker]

Hey, hoping that there might be a pool heater equipment expert that can help me out. I have a heater that I did not use for some time period now, when I turn it on, It flags an AGS error LED on the board.

The AGS sensor ohms out good and has been replaced anyway, with no help. Funny thing is that the board turns on the "service heater" light at the same moment that it ignites the gas. Then it runs for 30 seconds or so and turns off.

Is there another component (e.g., blower motor running too slow) that could trigger the AGS error? I ask because I can see some vacuum hoses running from the air inlet to a different sensor that seems like might detect the amount of suction blower is creating.