Albert Barnes Commentary 2 Chronicles 24:2

"And Joash did that which was right in the eyes of Jehovah all the days of Jehoiada the priest." — 2 Chronicles 24:2 (ASV)

Jehoiada lived at least 23 years after the accession of Joash (2 Kings 12:6). Thus, the idolatries of Joash were confined to the last 10 or 15 years of his reign (2 Chronicles 24:18).