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Q: Rough transmission shifts make the whole car move

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At just under 80,000 miles, the automatic transmission in my 2010 Kia Optima is rocking the whole car every time it downshifts while I am slowing down. What can I do about this problem now that it is so noticeable? Is the transmission going to have to be replaced?

A: This problem could be caused by electrical ...

This problem could be caused by electrical or mechanical issues with the transmission. It is very possible that the motor or transmission mounts in the engine compartment have failed. These rubber mounts or “isolators” subdue vibrations from the drivetrain to the structure of the vehicle. When they degrade, it can cause banging or vibrating throughout the entire vehicle. It is generally noticeable when shifting from drive to park or when downshifting. Another possibility is that the transmission control module needs to be reprogrammed. If the coding inside the module is incorrect, it could be sending incorrect signals to the transmission. It could also be dirty or contaminated transmission fluid. I would recommend having the transmission and mounts diagnosed by a certified mechanic, such as one with YourMechanic who can perform the diagnosis at the convenience of your home or office.

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