Started yesterday! Leaving work and my Sonata 2.0 litre would not shift into 3rd gear. Turned around back to work and noticed there was a hard 1-2 or 2-3 shift shock, (like side stepping a clutch in a manual tranny). Also noticed no reverse. Checked the fluid level and condition of fliud. Dark in color, but no bad / burnt smell or taste of the fluid. Drove car home, 35 miles, in 3rd gear at 3200 RPM's and before I arrived home MIL lite came on. Checked code and found P0750 logged two different occations. Is there anyone out there who can enlighten me as to what my problem may be. Been a great little car and would sure hate to have to "put a bullet in it" Thanks for your response.

 

If the trans fluid is dark, suspect that there is a leak inside the radiator, thus the dark color. What color is the coolant?

So my guess is you need a new radiator, and a tranny flush (if you're lucky) might fix it.

 

There has been no loss of coolant level, prestone (neon green) anti-freeze is used, also no change in color of coolant. I did notice that when car shifted into OD was when the slipping started, not 3rd gear as I had posted. But still no reverse. Now appears that tranny is in "get home" mode. Starts off in 3rd with no upshift or down shift.

 

Well dark is a bad color for trans oil. Did you ever change it? P0750 indicates solenoid "A" malfunction in the trans. You might be able to replace that solenoid without removing the trans.