I have a 2006 Chevy impala that needs a Map sensor and I don't know where it'* located. It'* a 3.5L engine

Near the coil packs.

Will I see it when I take the engine cover off

sounds like you have a 3.8 L , it will be somewhere close to the manifold usually at the back as it senses vacuum changes. there are a few Chevrolet dealers that have online parts order with exploded views , if you still cant find try googling buy map for 3.8L impala.

LA1, They did offer a 3.5L in 2006...
I am trying to find a pic of the sensor on the motor, but was unable to do so, I did find a pic of the sensor though, although it is upside down in this pic, hopefully this helps a bit.
When you remove the cover you should be able to see it, most likely on the left side of the upper intake.

WILLIAM E Yup I have a 2006 Malibu with a 3.5. I believe they also offered a 3.9L and a V8 Impala

Here is a you tube video

That video is for replacing the MAF Sensor, they inquired about the MAP Sensor, it really won't help them with replacing the MAP Sensor.

Map sensor is located near the ignition coils right where the ignition cables from bank 1 cross over the intake to the coil packs.

Ha Ha Ha so it is