While I was playing GT Racing 2 on my Redmi 1S, I noticed the car was swerving slowly to the left even when I hold it straight. So I decided to re-calibrate the accelerometer and gyro sensors.
Goto your dialpad and type *#*#6484#*#*
You can also type *#*#64663#*#* to access Engineering mode.
You can also type *#*#64663#*#* to access Engineering mode.
As you can see the menu is still in Mandrin (Chinese). Scroll down to 29 and 31 to calibrate sensors.
*Update: Good news, Prince.Paul.K on the MIUI forums has done a translation to English on this. You'll need to download the apk prepared by him and push it to the system/apps folder. Follow this link.