Check engine light goes on and off

[GaryR3500]

I post this problem a few months back. I have a 2022 3500 6.7 cummins the check engine light comes on code 409 EGR malfunction. I tow a fifth wheel TT. The light comes on when towing, when I unhitch the trailer and drive it for a while the light goes out. When I hitch back up and drive a few hundred miles the check engine light comes back on. Has anyone had a problem like this.

 

[jws123]

I would check the wiring on your trailer or leave it un plugged to test could be shorting something out. I have seen weird stuff like that before if this only happens when your towing lol.