I'd back off and do the classic desensitising routine. That is work beneath his threshold and gradually narrow that threshold. What I'm relating to is my experience with Barker the Elder the 2nd and cars. We lived in town then and as a puppy she wanted to eat them up! I changed our walks to late evening when there was little traffic and I could move her away and have her sit for a reward while the car passed. Several rewards. It wasn't long until the fire truck could pass with sirens blazing and she would pay it no mind.

Right now, it seems to me like Cody is getting flooded and that's not doing good.