Karva chauth is a festival celebrated by all married hindu women. They observe a fast for the long life of her husband. But Gurbani rejects such rituals.Fasting is not approved in Sikhism.
“One who discards this grain, is practicing hypocrisy. She is neither a happy soul-bride, nor a widow".
The only way to attain God is by singing His Name and following the true path shown in Sri Guru Granth Sahib.
https://khalsaforce.in/sikhs-do-not-celebrate-or-keep-karva-chauth/
Dr. Gurdeep Kaur
Associate Professor
Sri Guru Nanak Dev Khalsa College
University of Delhi