P1870 Code - Transmission Component Slipping so it seems like the transmission is worn out, but you can try a service to see if you can get a few more miles out of it with a new filter.
This guide can help you with the job:
https://www.2carpros.com/articles/how-to-service-an-automatic-transmission
If not here is how to remove the transmission for a rebuild. Also, this video shows the job being done on a different car, but the process is the same.
https://youtu.be/3vJAojsrfuU
Check out the images (below). Please let us know what happens.
Images (Click to make bigger)
Monday, February 20th, 2023 AT 6:15 PM