Forty Feet High and It Kills! - S2-E3
Revealing mistake: McGarrett and Victoria watch surfers from the beach. Thanks to the insertion of stock footage, they "see" surfers riding huge 6-foot waves. But in the shots of the actual locale behind them, the ocean is virtually flat. (00:09:30)
Answer: He was fired. He never really appreciated his character. He felt Kono was portrayed as a big dumb Hawaiian and that the stereotype was racist. He also felt underutilized. He was fired after a heated argument with the show's publicist regarding his character. It seems there's not much details given regarding the incident or the firing, so it's seems possible he upset the show's producers as well.
Bishop73
No he said something derogatory about one of the Jewish producers that's why he was fired.