I started having regen issues late last year with my XR 4046. It would go into regen mode like normal then one regen light would go out and the red warning light would come on. I would continue running it and the regen lights would go back to normal then relapse back into warning mode. Finally it went into limp mode and would not come out of it. My dealer is great and diagnosed the problem. Had to have a new burner kit installed which wasn't cheap but 100% fixed it. Just thought I'd add this to the discussion.