To leave the low priority queue and avoid its penalties, summoners need to complete at least five matchmade games without abandoning the matches early. Declining or not accepting a match will also result in the queue's timer being reset.

Why do I have low priority queue?

After leaving a few games, you will be placed into a low priority queue; as long as you can complete 5 matchmade games without leaving, you will be returned to the normal queue. However, if you continue to leave games, you will remain in the low priority queue.

Are LOL priority queues low?

Low Priority Queue After leaving or idling in several games, players will be placed in low priority queue for 5 games. While in low priority queue, players will have to wait an additional 5 minutes before being able to queue up for a match. Continuous leaving or idling will increase the AFK tier by 1.