1 Kings 22:43
And he walked in all the ways of Asa his father; he turned not aside from it, doing that which was right in the eyes of the LORD: nevertheless the high places were not taken away; for the people offered and burnt incense yet in the high places.
Jehoshaphat began to reign over Judah at thirty-five years old in the fourth year of Ahab king of Israel, and he reigned prosperously for twenty-five years. He profited from the training and example of his father Asa, who in nearly every crisis did what was right in the eyes of the Lord and turned not aside from it. He himself was loyal, seeking to walk in all of Asa's right ways without turning aside and doing what was right before the Lord throughout his reign.
Nevertheless the high places were not at once taken away, for the people still offered sacrifices and burned incense there, so his loyalty did not mean idolatrous practices were immediately removed. They remained because many had not prepared their hearts unto the God of their fathers and still clung to idolatrous practices, which troubled the king in his effort to rule wisely. In time, as reformations were wrought, he took away the high places and groves out of Judah.