I recently upgraded from my 2003 c240 with 300k miles on it. Had that car since high school and it still runs, but just wanted an upgrade. I have done all the maintenance on it myself and have become very comfortable with working on cars.

About a week after purchasing the C300, I wanted to change all the filters, fluids, etc to make sure the car is going to be on a maintenance schedule I know & to just make sure the car is taken care of. The car was running perfectly after I did everything, except the transmission fluid…

I dropped the tranny pan, filter, and attempted to drop the valve body to inspect, but it was giving too much resistance that I just called it and bolted it back in to prevent damage. After I let everything drain out (excluding the TC) I put everything back together, got some fluid in there, started the car to get it up to temp to properly set the level & after I turned the car off, it would not turn back on. To save time and stop rambling, I checked everything over, and over and over again. Starter, battery, relays. Everything checks out. I do have one code it’s throwing and it’s for the transmission. Y3/8s1, selection range sensor. I ended up dropping the valve body to inspect it again and check out the range sensor, and when I did this, I pulled off the sensor from the conductor plate and didn’t realize it was soldered on….. I’m going to solder it back tomorrow, but wanted to get everyone’s advice and see if you think that I possible messed something up with that when I originally tried to drop the valve body. Again, I never got the valve body out the first time. Just loosened and tried to pull it out before giving up. Can anyone feed in and give me some advice? Thank you so much. Let me know if you need anymore info.