Charles Ellicott Commentary 2 Kings 12:3

"Howbeit the high places were not taken away; the people still sacrificed and burnt incense in the high places." — 2 Kings 12:3 (ASV)

But.—Except that; as in 2 Kings 15:4. (For the statement of the verse, compare to 1 Kings 15:14.)

Sacrificed ... burnt.—Used to sacrifice ... burn. The worship of the high places continued even under the régime of Jehoiada.