Home › Forums › Stay Dirty Lounge › Service and Repair Questions Answered Here › Used Car Transmission Light › Reply To: Used Car Transmission Light September 25, 2020 at 5:38 am #963844 Richard KirshyParticipant The choice is up to you. You could scan for codes, but if the transmission was changed, you would assume the shop that did it would have checked and repaired the issue. Now, if it was a DIY replacement who knows what may have transpired.