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i have a 2009 2.4 sonata and it just started to act up yesterday morning i start my car to warm it up and i start to drive and im coming to the light and it jerked while i was breaking could it be miss firing? or is it the tranny? if its misfiring how do i take the plastic cover off to change spark plugs?:D
 

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wat exactly do you specifically mean by jerked? like jolted back while slowing down? could be a rough downshift due to the cold tranny. did you excssively brake or just gentle brake?
 

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Discussion Starter #3
i gently brake.. and while im braking one quick jerk yeah kind of like a downshift but how you fix a cold tranny then?
 

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go check the fluid first! could just be an easy fix. how many miles are on it? its probably never had the tranny serviced.
 

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I have had the exact same issue with my 09, starting about 1 week ago. I took it to the dealership since it still under warranty and had them check it out. The said there was a TSB to update the transmission, i guess through the ECU, they said they drove it and didn't notice it. Well I got in it and this morning and the same problem, only when the tranny shifts from 4 to 3. I only have 47k on mine, but called the dealership back up and they suggested getting the trans fluid drained and flushed and if it keeps having the issue then call them back up.

Let us know if the trans service helps your issue, I am going to be getting mine done in the next few weeks, I dont drive the Sonata everyday, i drive an older subaru to keep the miles low.
 

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Well I took my car back to the dealership and they checked it out, after the service lady told me that she thought it needed to have the transmission flushed and serviced I was unhappy with her. I talked to the service manager and told him my issue, he had them check it out again, after they "flashed" the memory from the transmission it seemed to get better but then he checked some other things and it turns out there was a sensor that he said was the mass air flow sensor, they changed it out and the car seems to be running great now. He said the sensor was reading temps wrong and it was causing bad shift points.
 

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2009 Sonata Problem

I am having the same problem with my 2009 Sonata. It only happens when my car is cold (after sitting overnight or all day) even if I let it run to warm it up. It drives fine but then when I go to break, it jerks once. After driving for a bit, when the car is warmed up, it no longer happens. I hade my transmission serviced and my brakes checked...nothing.

What did you find out??

Thanks. :)
 
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