I've had this 97 Deville D'elegance since about May 29 of this year. I've had problems on and off with it. I've taken it back to be reparied by the dealership a few times. I was constantly getting the PO300 code before. I've had it back about a week and a half now and the service engine soon light comes on AGAIN. They told me the last time I went to pick the car up that it was the fuel injectors that they had to replace. When I checked the codes this morning I got 17 codes!!!. They are all history codes ranging from P0300 to u1146(which was a current code up until about 20 minutes ago). My question is where all these codes just activated during the repair of my car or is something really going on. The u1146(lost northstar communication code) was current this morning and history this morning :helpless: . Should I just clear the codes and see what happens? If so hwo do I clear the codes? Any help is much appreciated.

P0300 is a misfire detected code. Yes, I would clear the codes and see if they return. Enter the diagnostics. After the codes are displayed it will ask PCM?. Answer yes by pushing the HI FAN button. Answer no to the next prompts with the LO FAN button til you are prompted CLEAR PCM CODES?. Then obviously answer yes.