Not starting

Car just shut off at a light. Have had no issues until it just shut off while out driving. Was told crankshaft sensor was bad. Replaced it. Car started a few times while parked. Drove away stop and added oil. Turned car off while adding oil. Car wont start again. Told bad part. Replaced crankshaft sensor again. Car started several times while parked. Drove home later that evening went to leave and car wont start again. It will crank over and over but will not fire. What could it be? The research I've done is leading me to the camshaft sensor. But unsure and not a lot of money to play elimination. Thank you