[iamnotnot]

CRV 2003 A/T - Jerk or shift shock from 1st to 2nd gear when the engine is newly started, but all gears shift smoothly after a few minutes.

The 'D' light sometimes blinks, but after restarting the engine, the blinking stops. When I scanned it, there was a code P0750.

Does anyone encountered this problem?

 

[RustyBumper]

I have not had this issue but a quick search says it has something to do with transmission solenoid A.
Do you know when the last time you maintained the transmission?
Have you checked the fluid level and color?

 

[iamnotnot]

Yes sir, new honda transmission fluid

I forgot to mention, this all started after I let the mechanic fix the leak issue on my crv's transmission.

After he put back all the parts. it all started. blinking D, jerking on 1st gear to 2nd gear

I don't want to bring my car back to that mechanic anymore.

I will try to change the shift solenoid A myself. This is it right?

 

[RustyBumper]

I have never had to work on the tranny solenoids, so I would not be able to verify your picture.
One good site to verify parts and part numbers is hondapartsnow.com
Also, it is recommended to only use genuine Honda fluids for the transmission. In this case DW-1. I am not sure how aftermarket solenoids react in the Honda tranny, maybe someone else will chime in on their experience.

I should also mention to first test the solenoid for ohms and function before you spend money on a new one. It may just have a poor connection. There is a very good YouTube video on testing these.