Need help! Transmission issues? Unexpected downshifts, VSA and caution light.
 

First off, I've tried researching this problem but I am not finding solid info or I'm finding things similar to my case but not exactly. If this has been discussed before and I'm just a google noob, please excuse me.

So, about 2 weeks ago I was driving to work, about 45 or 50mph, in 5th gear (car was just in D, not sport shift) when the car very harshly downshifted into 4th, and threw the VSA and /!\ light. I tried moving it into sport shift mode but it would not allow me to move out of 4th. When slowing down, the car will harshly downshift again. Also note, the car is in a limp state and would not allow me full power. Anyhow, I made it to a parking lot, turned the car off and crossed my fingers. I restarted it and the lights went away. :preach::bow:

Since the start of this problem, it has occurred about 4 more times. I had the CEL scanned and it's returning codes P0443, P0497 (both EVAP) and P2138. Now, after some research I've learned that P2138 is my throttle position sensor, which is causing my car to hesitate on acceleration from stops and also giving me difficulty while trying to maintain a speed.

My question now...is my problem with downshifts related to the throttle position sensor, or is my transmission beginning it's early stages of death? :sad:

Thank you to anyone who replies, it would be a great help.

https://acurazine.com/forums/problem...-light-690295/

I did find that old thread, it is exactly what has happened to me, unfortunately, OP hasn't updated his thread.

Start with the Accelerator Pedal Position (APP) sensor first.

Instead of replacing the sensor, you might try an adjustment of the throttle cable per this thread: https://acurazine.com/forums/problem...-doing-830989/

OP

Fix the codes first... address the trans last. If you're lucky the trans is fine.

Have you try to replace the transmission range switch sensor? Its easy to do. When mine start to fail it wont let me shift from 2nd to 3rd either via padle or at the gate cause the car to bouce on the rev limiter.

I haven't even heard of that part. It sounds similar but isn't exactly what I'm experiencing.

For the 5th to 4th gear shifting. Try replacing the following.

1. Shift Solenoid Valve C.
2. Pressure Solenoid Valve D.
3. Pressure Solenoid Valve C.

This same thing happened in my 05 5AT. I had the throttle position sensor replaced and that solved the problem.

This seems to be the general consensus. I have since replaced mine a few days ago and have yet to experience it again. Knock on wood, I hope it stays that way.

I am happy to report that after replacing the throttle position sensor, the problem has not occurred. :)