ECM replacement and location

This code does not mean replace the pcm or the mass air flow unit (A/F sensor). I would is get some mass air flow cleaner (nothing else) and clean the mass air flow meter. After cleaning it reset the light with a code reader and see if it comes back. If it does then it may be an that we will have to run tests on the coolant temp sensor or the mass air flow meter to see what it causing it to run a bit lean.

This could also be a bad upstream O2 sensor, but as racefan pointed out, certainly not a PCM.

I totally agree thanks for that mm I forgot to mention the it could be an O2 too.

If you're talking about the engine locked/seized-up-I don't think so

I agree with Raz, not going to lock the engine.

Scan for codes and check fuel pressure with a gauge first auto parts rent it. Check for a vacuum leak

Doubt it's the box but until you do what I said in first reply you'll not know you have to start someplace

Sounds liike it could be failing, let me know the following to help rule out others possibilities;

Has the O2 sensor code been cleared for a period of time and then it got thrown again?
Are the trouble codes for various things or are they maintenance type items?
Do codes clear themselves?
How frequently are codes being thrown?

I will keep an eye on this and get back ASAP.

No it definitely does not. Sounds like they are not sure of their diagnosis of the original problem of a evap system leak. Usually I find that the vent solenoid on the charcoal canister is faulty causing this code. Probably code 440 or close to it.

Hi,

Is the P0171 the only code you are getting? When you checked for vacuum leaks, did you check the intake? Is the fuel pressure within the manufacturer's spec? Low pressure can also cause a lean mixture.

I have one last question (sorry for so many). Do you have a live data scan tool? If you do, check the short-term fuel trims and also confirm the coolant temp sensor is reading correctly.

If you look at the attached pic, it shows the possible issues. If you haven't, check fuel pressure first. Also, confirm there are no vacuum leaks in the air intake tube between the airbox and throttle body and the intake manifold. Also, if you have an engine vacuum gauge, let me know the reading at idle.

Here is a link that explains how to check for a vacuum leak. Note that the smoke test shows leaks in the EVAP, but can miss something in the air inlet or intake. Also, check the PCV to see if there is an issue there as well.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

If you look through the remaining pics, they provide diagnostic procedures. They cover everything that can cause this code.

If you haven't already, confirm fuel pressure and check again for a vacuum leak. Here are the manufacturer's specifications for fuel pressure. If you don't have fuel pressure gauge, most parts stores will lend one to you.

2007 Toyota Corolla L4-1.8L (1ZZ-FE)
Pressure, Vacuum and Temperature
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Pump Fuel Pressure Specifications Pressure, Vacuum and Temperature
PRESSURE, VACUUM AND TEMPERATURE
Fuel Pressure .................... 304 to 343 kPa (3.1 to 3.5 kgf/sq.cm, 44 to 50 psi)

Fuel pressure for 5 minutes after the engine has stopped .................... 147 kPa (1.5 kgf/sq.cm, 21 psi) or more

_________________________________

Let me know what you find or if you have other questions.

Take care,

Joe

See pics below.

Hi,

Check the OBD fuse in the instrument panel fuse box. It is a 7.5 amp fuse. Chances are if the scanner was damaged, the fuse is bad.

Take a look at the two pics below for identification and location. In addition to checking the fuse condition, confirm there is power to and from it. Here is a link that you may find helpful:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Let me know what you find or if you have other questions.

Take care,

Joe