The most common issue and overlooked thing when installing the H&S Mini Maxx is thinking the tune has been installed when in fact it has not been.
If your check engine light is on after installing; 99% of the time its because you didn't not follow the on screen instructions properly. Read & Clear the Diagnostic Trouble Codes (DTC's). If codes and check engine light are still on; verify the tune status: Go into the Menu < Settings < Tune Status.
If tune status shows "Not Installed" go back and reinstall. It will ask if the DPF is present or DPF removed. Be sure to select DPF removed.