I know the block drain plug is on the driver side of the engine. Why do you have to take the knock sensor out (it's on the ECM, right?).

 

Nope the sensor is on the left hand side of the block. The knock module is in the ECM.

 

No, the knock sensor is on the right side of the block. (L and R is viewed from inside or behind the car looking forward)

The knock sensor is in a hole that would otherwise have a plug in it. Pulling one plug out will not drain the other side of the block.

 

After taking the driver side drain out and putting it back once, I will never do it again. That is the most impossible to reach bolt I have ever dealt with. I finally bent a 12 point box end with a torch and managed to get it in, about 2 deg. at a time once I finally got it started.