Mass Air Flow sensor location '99 Yaris

[MrNinety]

Hi,

I'm looking for the MAF sensor on my '99 Yaris.

About two weeks ago while driving, the CEL came on and stayed on for the
rest of the trip. Connected my ODBII scanner when i got home and it returned error code "P0171 - Powertrain - System too lean (Bank 1)"

Did some research and found some information about the STFT (Short
Time Fuel Trim). When idle, the STFT should be close to zero
and if it elevates to 15-20% it could be a faulty MAF sensor.

I drove around for a bit and logged the STFT, and this is exactly what happens.

A new sensor is about €280,- so i rather try cleaning it first. There are
sensors on both sides of the air filter box. Does someone know which one
is the MAF?