While slowing down I feel a clunk sound, transmission will not go into overdrive

Good morning,

Are there any codes in the system?

https://www.2carpros.com/articles/automatic-transmission-problems

I would start by changing the fluid and filter in the transmission. It sounds like a valve in the valve body is sticking.

https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

Roy

Yes there are codes. Here is what I have: Po736, po841, p1776, p0300, p0700, p0481.

Thanks.

The 700 is an information code.

the 300 and 481 are engine codes not related to this issue.

I posted the possibilities for the other 3 below. They all indicate electronic controls such such a sensor voltages and returns. You will need an advanced scan tool to monitor the live data for these sensors and solenoids.

The one code for 736 is my concern. It is indicating excessive slipping inside the transmission from worn clutches. This is an indication the transmission will need either a rebuild or replacement.

Roy

When I bought the car there was a transmission solenoid. And a transmission filter in the trunk. Should I change all that and new fluids first?

You can try but I doubt that will resolve it for you.

Sounds like someone was guessing.

Roy