The fact that there is a sale on doesn't tell you which routes are in the sale nor which travel dates the sale applies to. The routes and dates which are not in the sale will not have sale fares.

The corollary is that many sale fares are routinely filed without the airline either marketing them as sale fares, or generally marketing a sale.

The price and the fare rules will tell you whether a fare is a sale fare. Typically, you're looking for fare in the relevant booking class(es) that's significantly lower than standard fares, and which has a short "ticket by" date or window.