Engine light came on with P0101 and P0102 codes?

2015 TOYOTA COROLLA
175,515 MILES • 1.8L • AUTOMATIC
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RLPETERSON78
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I took my car to a trusted mechanic and first they replaced a gasket on my gas tank. I took my car to be emissions testing and it passed. Then my car got a lot of codes and I took it back and they replaced the charcoal canister. I drove it for a few days and then I got a P0101 code. I took it back to them and they replaced the connector to the Mass Air flow. I drove it for three day and the engine light came back on. I took it back to them and they kept my car for 3 weeks.I need my car back so now I have it. Last night the engine light came on with P0101 and P0102 codes. The mechanic said that my Mass air flow sensor was working fine. I have attached a page that was in the car when I picked it up. Where should I be looking to solve these codes?
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Aug 11, 2026 at 8:18 AM
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RLPETERSON78
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I dover my car over 50 miles and didn't feel any thing that felt like a Mass air flow sensor, no stalling, accelerated fine and non of the thing that s bad airflow sensor would do. It like the code are phantom.
Aug 11, 2026 at 2:53 PM
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JACOBANDNICKOLAS
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Hi:

The codes indicate low voltage to the MAF sensor. I noted that they replaced the wiring and connector to the MAF. Have they replaced the sensor itself?

I checked what was indicated on the receipt, and the voltages are within spec as far as power supply. He also indicated a good ground, so the last things left are the MAF sensor itself or something is happening with the PCM.

Let me know if the sensor was replaced. If it was, check what brand was used. I'm seeing a lot of low cost parts that aren't any good.

Let me know.

Joe
Aug 11, 2026 at 7:05 PM
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RLPETERSON78
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They said that they checked the Mass air flow sensor and it was good. The Mass airflow sensor is a Toyota Denso. See the photos
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Aug 11, 2026 at 7:20 PM
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JACOBANDNICKOLAS
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That is where I would start. You can get cleaner for the sensor to try cleaning it.

Here is a link that explains how. Keep in mind, they indicated the power supply is where it should be. The more I think about it, that wouldn't likely be the case if there was an issue with the PCM. That is why I'm suggesting starting at the sensor itself.

https://2carpros.com/articles/mass-air-flow-service/

Let me know.

Joe
Aug 11, 2026 at 7:36 PM
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RLPETERSON78
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I have already done that. I have cleaned it two to three times. I cleaned it before I took it back to them to fix the codes. They couldn't fix it and I need my car. Should I call Toyota tomorrow to get a mass airflow sensor?
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Aug 11, 2026 at 7:43 PM
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JACOBANDNICKOLAS
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Hi:

Other than replacement, you can try testing it at home. All you need is a multimeter.

Here is a link that explains how it is done at home. If you scroll down a bit, you will find the directions for testing with a multimeter.

Let me know if that is something you are comfortable doing.

https://axleaddict.com/repair-maintenance/how-to-test-maf-sensor
Aug 11, 2026 at 7:55 PM
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RLPETERSON78
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It was already tested. It was in the first page I sent you.
Aug 11, 2026 at 7:59 PM
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RLPETERSON78
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I started the car and then I removed the Mass airflow connector and the engine shut down, Just like turning the car off. After that it threw a code and when I checked it it was all the stored codes in the ECM and no current codes. Before the mechanic took my car to the Toyota dealership and they confirmed that the ECM was working good and no update needed. So I don't what is causing the codes. Any thoughts?
Aug 12, 2026 at 10:14 AM
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STRAILER
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Yes, I would replace the MAF sensor, cleaning it when it is too far gone does not help. After you have replaced the part, clear the codes and drive the car. Also I noticed the new MAF pigtail so it might be wired incorrectly. Here is the wiring diagrams so we can double check it.
Aug 14, 2026 at 10:56 AM
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STRAILER
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Here is the diagram
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Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Aug 14, 2026 at 10:59 AM
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RLPETERSON78
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I replaced my Mass airflow sensor with a Denso Toyota. And after 250 miles driving there are no codes. That solved the problem.
Aug 29, 2026 at 5:09 AM
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STRAILER
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NICE! Good job on the fix and thank for letting us know, please come back if you need us.
Aug 29, 2026 at 8:03 AM
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