My mechanic went with the car to the local Toyota dealer. The Toyota dealer said that the error code was related to the DPF but I still don't know the exact error code... The dealer did 2 times a forced regeneration but he said that it was not guaranteed that the problem was solved with this regeneration. He said when the error shows up again I need to replace the DPF. This is a very costly replacement. My mechanic told me that there also "unofficial" DPF's out there. Is this a possible solution