Suburban water heater won't stay lit.

[Edgardewey]

The water heater on my 2018 3721RL won't ignite on its own. I can light it with a lighter, but it only burns for a few seconds and then goes out. I replaced the ignite and that didn't help. Them electric mode works fine. Amy suggestions? Coupler or control board? And where is the control board on my unit? Thanks.

[Daryles]

Does it spark when you turn it on gas mode?
BTW, to first operate in gas mode the water temperature must be below 100⁰F.
I had that problem first time. Ran the hot water until it ran cold then tried it again. Worked fine.
I would start with the thermocouple.
There is a Suburban water heater manual in the files section
https://www.montanaowners.com/forums...hp?do=cat&id=3

Page 28, flame sensor.

[rohrmann]

The flame on the water heater does not stay on, only comes on when the thermostat/high limit switch for the gas mode calls for heat. The electric mode works the same way, only it is for 120 volts AC. The gas switch is for the 12 volt DC system that operates the gas side.