lift up the car , standing underneath it it is the first barrel looking thing in the exhaust. You will notice an O2 sensor (with wires attached) immediately before AND after the cat.
chain
The 2003 Toyota Echo takes 22" drivers side and 14" passenger side replacement windshield wiper blades.
108
when it breaks
3.6 litres
Its included in the following instructions for changing out the post cat O2 sensor. http://www.carspace.com/guides/Toyota-Echo-How-to-change-post-catalytic-O2-Sensor
It is underneath
$1500 to $2000
There are none.
4 x 100
Needle nose pliars.
It is 30mm