Nickels626

i know that the code 42 is a speed sensor error but i just want to know in what way can i fix this problem? i also know that the code 52 is a knock sensor code but i dont know were the knock sensor is and how i can fix this problem? i need help with this so please help me.

i have a few issues such as rich burning, turbo not fully spooling up, sounds like its missfiring (like a diesel engine sound), lack of power in all gears and wont go anywere past 4000 rpm's. if anyone knows what the issue, please help me out.