2010 toyota prius cylinder number 4 indentification

Stand on the right side of the car with the hood up You're looking straight down at the front of your engine at this point The number one spark plug is the closest to your body number two three and four are right behind so the number for spark plug when you're sitting in the car would be the one closest to your probably right knee so if you're standing in the front of the car It would be the last spark plug on the left closest to the driver the one on the far right closest to the passenger is number one

 

Cylinder #1 is closest to the front of the engine. The front of the engine has the harmonic balancer and accessories (water pump, etc). The rear of the engine is connected to the transmission.

Cylinders are numbered in ascending order starting from the front to the rear.

 

What's the miles on it? Has the EGR system ever been cleaned?

Cylinder numbering:

 

Same poster with the bad egr

 

Ah, the ol' double thread trick.