Where do i find the 31 vaf sensor curcuit on a 4s camry engine

24 is an air intake temperature circuit fault
31 is a fault in the MAP sensor circuit or air flow meter circuit.

It may be that there is a short or corrosion in the wiring connections to that area of the engine intake tract. Disconnect and reconnect these a few times to see if the fault is cleared.

Note: to clear trouble codes you will have to remove the EFI main fuse for 30 sec. See here p 299

http://www.turboninjas.com/camry/eg1.pdf

The output of these 2 codes simultaneously points to the ENGINE coolant temp sensor ground circuit being broken somewhere (E2 connection). See above link p356. Using this info you can also test the sensors in the air intake.

code p 101 refers to mass air flow(MAF)sensor/volume air flow(VAF) sensor --range performance problem====causes --intake leak/blockage---MAF/VAF sensor

code p 0171 refers to system to lean bank 1===causes ---intake /exhaust leak---AIR system---MAF/VAF sensor ---fuel pressure/pump---injector/s---HO2S ( heated oxygen sensor --the one in the exhaust manifold before the cat converter bank 1)

I don't have a listing for the c code but from the other 2 codes I would be checking around the maf/vaf sensors and the HO2S sensor (replace)
start with checking the wiring and connections to both units

check the volume air flow sensor(VAF) as well--low input or range /performance problem===causes--intake leak/blockage--VAF sensor---wiring short to ground --VAF sensor.

code p0171 refers to system too lean bank 1==causes intake /exhaust leak--AIR system--MAF/VAF sensor--fuel pump /pressures--injector/s--HO2S sensor

The easiest one to check is the HO2s sensor before the cat converter in bank 1

P0171 System too Lean (Bank 1),Here's what is listed for the code.OXYGEN SENSOR.

Your corolla doesn't use a MAF sensor, it uses a MAP sensor

The map sensor is located on the Intake Manifold right by the throttle body. That could easily be causing the issue you're stating.

turn key on --key off ---key on -- key off ---key on , then you should get the codes from the check engine light.

i had the same problem on my 96 monte carlo. its the mass airflow sensor. the sensor is dirty and needs cleaned off or, you need a new one, or you have a short in you MAF wiring. It could also be a vacuum leak. hope this helps.

p0443 is evaporative emission control system, purge control curcuit malfunction, p0449 is emission control system, vent control curcuit malfunction. p0449 is often a filler cap problem on fuel tank. try tightening cap

maf or vaf A curcuit low input, po141 is 02 sensor bank 1 sensor 2. this should be the 02 sensor after convertor,