2014 Mazda3 GX P0171 Code

[24CX-5GS-RW]

Hi everyone,

My dad's 2014 Mazda3 2.0 GX 6 speed auto has been running great since we got her new.

It has around 85,000 km and we live in Edmonton, AB Canada.

About 2 months ago my dad went for a tire swap at Fountain Tire and noticed Check Engine Light after picking up the car.
2 days later I bought a Ancel AD410 Pro Upgrade 2025 OBD2 scanner to pull codes and got a P0171.

I noticed during acceleration the engine sounded off; the noise was droning, and idle noise could be described as up and down?
Engine was vibrating too.

I checked and it seemed light the engine air filter box wasn't secured. Fountain Tire denied all responsibility...
The car runs fine. now until yesterday when it has the P0171 code. I've checked the air filter box, gas cap etc.

I can also do live data but unsure what to look for. It might be MAF sensor is dirty, or O2 sensor is bad?
But I've read online and it seems these 2.0 Skyactiv-G engines have GDI and around 70,000KM we need to clean the fuel injectors with something?

Will this resolve the codes?

 

[negusm]

That's a too lean code.

You probably have air getting into the system.

Look for a vacuum leak. Check all the hoses for cracks or breaks. Use the brake cleaner spray trick to find it. (lots of videos)

You can test the O2 sensor but I'm thinking, since the car isn't running right, the sensor is working and telling you something is wrong.

Cleaning the MAF is always a good idea. It's possible that injectors are not spraying enough so you can run some cleaner through them. Won't hurt anything.

Also, clear the code and does it come right back or does it take like 2 weeks? If it's 2 weeks, it may be the O2 sensor is not working well and is starting to go.

 

[24CX-5GS-RW]

That's a too lean code.

You probably have air getting into the system.

Look for a vacuum leak. Check all the hoses for cracks or breaks. Use the brake cleaner spray trick to find it. (lots of videos)

You can test the O2 sensor but I'm thinking, since the car isn't running right, the sensor is working and telling you something is wrong.

Cleaning the MAF is always a good idea. It's possible that injectors are not spraying enough so you can run some cleaner through them. Won't hurt anything.

Also, clear the code and does it come right back or does it take like 2 weeks? If it's 2 weeks, it may be the O2 sensor is not working well and is starting to go.

Thanks dude. Idk about the readings but I'm thinking of cleaning MAF sensor (car starts and runs so it still works, didn't go bad), and since it's GDI I'll buy LiquiMoli or BG44K injector cleaner to thoroughly clean the system through the fuel tank.