It doesn't use a Map sensor , it use a MAF sensor , and it is located right on top of the Air filter box
The one closest to the exhaust manifold is the upstream O2 sensor.
You can get a refurbished one for about $70. See: http://lmgtfy.com/?q=toyota+echo+mass+airflow+sensor
To remove the passenger seat from a Toyota Echo, first, locate and remove the bolts securing the seat to the floor using a socket wrench. You may need to move the seat forward or backward to access all the bolts. Once the bolts are removed, disconnect any electrical connectors for power seats, if applicable. Finally, lift the seat out of the vehicle and store it in a safe place.
It is inside the Mass Airflow Sensor (MAF sensor), IN OTHERS WORDS IS PART OF THIS.
Right next to the air filter.
See related link which includes instructions for testing any O2 sensor.
The 2002 Toyota Echo OBD 2 port is under driver side dash next to kick panel
the price i paid at the local Toyota dealer was around 177.00 for maf on my 2000 Toyota echo stmptoms were car weak power delayed fuel pickup this fixed it.plenty of power now
See related questions.
It is conveniently located inside the fuel tank :)
It could be anything from transmission speed sensor to just a broken speed cable.