Car jumped and raved 4000 rpm’s won’t go over 25 mph?

Hello,

P0734 means “Gear Ratio Error in 4th.” The computer commanded 4th gear, but the input/output speed relationship showed that the transmission did not actually achieve the expected ratio. P1790 means “Fault Immediately After Shift.” So this can be the transmission is going bad or it is low on fluid so that is where I would go next. Here is how to check it, I would smell the fluid as well so you can tell if it is brunt or not.

Thanks fluid smells good, it’s redish in color, no burnt smell the van had a brand new transmission put in last year. We purchased it from our neighbors. It was running great even made a two hour trip with it. Drove fine. I just received dip stick to check fluid. I did try the oil stick method that seemed like it was over full, but won’t know until I check it with new/ universal dip stick. I was hoping it would be a wee bit cheaper fix since it’s already had a new transmission put in, and it’s only got 117.000 total miles

Okay, this can be an internal transmission issue or the input shaft sensor is bad, here is the location so you can swap it out, please clear the codes once completed.