Sonata: P0715 P1529.. even after replacing input speed sensor

I have a Sonata 2002 LX, with a 'check engine light' problem. I took
it to Autozone, the codes were P0715 and P1529. Based off what I'd read
here, I bought an input speed sensor and replaced it. There was no
problem for a day or 2. Now again, it throws a check engine light. What
should I do, if it's not the input speed sensor?

 

Oh.. and just to add.. after replacing it and driving in the auto mode,
the car took it's time in shifting gears.. It would go to above 3000
rpm before shifting to the next gear..

 

First, check your work. Make sure the input speed sensor is plugged in and
bolted in properly. If you replaced the correct sensor, you had to move
the shift cable bracket to get it out.

I'm presuming you cleared the codes after repair. If so, go have the
codes reread and see if they're the same. I've had a couple cases where
the input sensor failure occurred in rapid succession with an output
sensor failure.