My daughter just purchased a new grand cherokee diesel. At approx three thousand miles, warning appeared and jeep would not exceed 30mph. Took to dealer and they had to do a manual regeneration. They could not answer why it did not regenerate on its own, nor whether they fixed the issue for good. My question is, how often should the jeep be regenerating..she has put on an additional 1000 miles since the service and no automatic regeneration has occurred. Anyone else have that issue??