John Gill Commentary 2 Kings 16:1

"In the seventeenth year of Pekah the son of Remaliah Ahaz the son of Jotham king of Judah began to reign." — 2 Kings 16:1 (ASV)

In the seventeenth year of Pekah the son of Remaliah Ahaz
the son of Jotham king of Judah began to reign .
] Jotham began to reign in the second of Pekah, and he reigned sixteen years, and therefore his last year would fall in the eighteenth of Pekah; but as his first year might be at the beginning of the second of Pekah, his last was towards the end of the seventeenth of Pekah's, as here; see (2 Kings 15:32) .