I have a 2011 Sonata SE (paddle shifters for manual shifting), 2.4 with 174,000. One-owner and well maintained. Transmission fluid changed every 40,000 miles with Amsoil.

Problem:

The transmission when in "Drive or D" will sometimes switch to manual mode while selector is still in "D". The dash will show the gear the transmission is in and often attempt to further downshift for no reason. If I don't shift the stick into "Manual Mode" then back to "D", I fear it would shift down until the engine over revs. When I try to switch to the Manual mode and input an upshift, the transmission is finicky on shifting out of the gear it is in, and often ignores the input or just downshifts if it does respond to the upshift, shifting up. I have to move the console shifter back and forth from Manual to "D" to get the car to stay in the "D" mode, but the transmission often reverts back to the manual mode even if in "Drive."

I have scanned the computer and no codes related to the transmission are read. The car has a seat sensor for the SRS, but it has been on for a while and never produced this problem, it just generates a light on the dash with no issues but that the SRS is not working.

I'm thinking about changing the input and output sensors on the transmission, but thought I would post the problem on the forum to see if there is a solution to this issue. Any thoughts are appreciated as I won't work on the car until this weekend.

Thanks,

Barry