What year of car? I had to run an accessory power because my 2001 doesn't have a pin on the OBD2 for the gauge to power.

The hp/torque might be off, if you really want to be close then adjust the altitude you have it set on and such.

All stock gp's will read a few degrees of kr from factory. 3 isn't bad but its acceptable when your not modding and making more power than stock.