03 Auto 174K, No issues. For the last 30K I've done simple drain and fill every 10K with S(J)-matic fluid.

 

My trans only goes into 1st gear and refuses to go into any other gear, it only revs when it's supposed to go into 2nd etc. I reset the ECU but it still does the same.
At first I drove the car at 110 to 120 mph for 40 minutes on a hot day, the AT came on and the car ran hot...I pulled the car off the road to cool down...when i tried to start it with FOB ...nothing, I had to use the actual key to start it when it started it rode only in 3rd gear, so I parked it till the morning and then when i started it it would only drive in 1st gear. I reset the computer and then 3 codes actually came up P0462, P0615, P1815. i don't see the relevance in these codes to the malfunctioning of my car. I need some help on this issue

 

P1815 is a fault in the driveshift mode so yeah that would definitely cause a shifting error since it's probably stuck in manual mode.

 

It's not stuck in manual mode, it won't shift into any other gear but 1st. In manual mode, it won't shift to any gear but stay in 1st/auto mode 1st gear and when it is time to go to 2nd it will just rev like in neutral

 

Time to bite it, and take it to the tranny shop.

 

so ‘05 G35 is throwing P1815 code. Hard shifting and some slip sounds. Only 36k on it. Brother in law said it was stuck in manual mode when he test drove it. Took it to a shop and they want to rip me for nearly $3500 for new tranny. And the only code they got was P1815. So need to know how to fix this issue bc tranny doesn’t need replaced at 36k like they want to do.

 

so how do I fix the P1815 code/hard shifts and slips?