05 corolla hesitates & P0172

http://engine-codes.com/p0172_toyota.html I would replace the front O2 sensor by what I just read on your post. The site I posted will give you more info if you want.

If you need further help, reach me via phone at https://www.6ya.com/expert/steven_a67ead41eb5fc62a

Sounds like it is still lean & driven rich by PCM

I assume a repair shop can't resolve the issue !

That seems to be why thousands of people come
to this site & ask questions

I know the MAF is common to both banks, but you diagnose
short & long term fuel trim & perform several tests, before you
replace a MAF Sensor

Check engine light on ? Lean codes , fuel trims ? Causes of lean condition trouble codes P0171 P0174 GM 5 3L

Do you know what a professional type scan tool is ? What fuel trims are . How to find a lean condition ? Understanding Short Term and Long Term Fuel Trim an SD Premium video

sounds like a faulty fuel pressure regulator, i checked out code P0171 and that is correct.
good luck,
frank

DTC P0171 is set when fuel trim is driven rich beyond a certain value. Possible causes are:
1. Exhaust system leak.
2. Improper fuel pressure.
3. Fuel injector restricted.
4. Defective heated oxygen sensor No. 1.
5. Defective Manifold Absolute Pressure (MAP) sensor.
6. Defective Engine Coolant Temperature (ECT) sensor.
When the air fuel ratio feedback is stable after the engine is at operating temperature and the fuel trim has reached its limit of correction to the rich side. (2 trip logic).
Feedback from the HO 2 sensor influences short-term fuel trim and short-term fuel trim influences long trim fuel trim. Short-term values are temporary and not stored when the ignition key is turned off. Long-term values are stored in memory because they are part of the basic injection duration. Long term values affect injection duration in closed and open loop because they are used to calculate basic injection duration. It is important to remember that the actual fuel trim will be the opposite of the DTC. A system too lean, DTC P0171 will mean the ECM is making a + or rich correction.
read (and let me know)above data and Freeze Frame by using (example, generic) Scan Tool on # mode 2, etc.
Slowly accelerate the engine in the increments shown and record voltage,
grams/sec of MAF and SFT, LFT, Injection Pulse, Fuel Pressure, etc.
HTH,
Vehicle have MAF Sensor?

check plugs, wires, and coils for proper spark.

P0171 means Fuel Trim System Lean (Bank 1)

The MAF (Mass Air Flow) Sensor is dirty or faulty.

Note: The use of "oiled" air filters (K&N, etc.) can cause the MAF to become dirty if the filter is over-oiled

There could be a vacuum leak downstream of the MAF sensor.

If your FT is leaning it that much, I would suspect an O2 sensor or it's circuit is the problem. When that O2 sensor went to 2V, I think you found your problem. The O2S is telling the PCM that the fuel ratio is way rich, so the PCM is assigning a way lean fuel trim.

Replacing the Mass Air Flow Sensor should do the trick.

Rate this.

Have these things checked for #1:
Spark plug
plug wire
#1 fuel injector
and the throttle position sensor, also have a fuel pressure test done, especially for the hesitation.

Check the fuse to the injector. If it is out or got wet, it could mimic these conditions. let me know what happens. I have an 85 model.