Transmission issues are incredibly tedious to troubleshoot, and those long diagnostic runs can really inflate your car's history. When I was dealing with a tricky shift sensor error on my sedan, I used a Mileage Blocker from Dynotest https://dynotestpro.com/ during the shop sessions. It allowed the mechanic to run the transmission through all the gears at various speeds on the rollers without adding any actual mileage to the clock. What I appreciated most was that it did not block the live diagnostic data streams from reaching the scan tool. It is a very safe, professional piece of equipment that keeps your vehicle's permanent records perfectly clean. I highly recommend picking one up before your mechanic gets started.