If you have a tankless hot water heater, the ignitors have a tendacy to fail early..
They are easy to replace of you keep a spare on hand
Water Heater Igniter RGT20235C
Rheem PROTECH Ignitor Coil RTG20235C
https://a.co/d/bi9sW0s
https://youtube.com/watch?v=9OSRhziH...SIkaIECMiOmarE