Is this a exhaust leak? Cummins x15

Yes that’s an exhaust leak.

 

I would start with the clamp

 

I think it's an exhaust leak when cold, as it warms up, probably seals. I'd fix or tighten the clamp. I don't think it's related to any regen issues however.

 

If that clamp is on that bellow piece if it were me I’d pull the clamp at the other end and pull it all the way out so you can check it over good for cracks. Then if everything looks fine I’d replace both clamps.

Any loss in pressure can cause regen issues because it won’t build up enough heat to regen properly and this leak could be the reason he’s seeing gray smoke when it trying to regen. These newer trucks need to hold in a lot of heat down to the dpf for everything to work as it should.

 

The black soot around the clamp tells me its leaking ..

 

Shove some tin foil in the joint when you have it apart providing it’s not actually cracked