Mass Air flow issues?

2013 TOYOTA COROLLA
175,515 MILES • 4 CYL • 2WD • MANUAL
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RLPETERSON
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Hello,

I was having check engine light codes that pointed to the MAS airflow sensor. I bought a new sensor and that didn't solve the issue. I investigated the wires on the connector and found that two wires were cut. So I decided to replace the connector. The new connector came with shrink wrap connectors. I tried to cut the wires so the shrink wrap connectors weren't on top of each other. I wrapped the new wires with black tape and that cause all sorts of issues. Now I am getting more check engine light. I unwrapped the connector from the wire from the tape and is solve the problem. What was going on when the wires were tightly wrapped?
Sep 29, 2025 at 12:39 PM
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BLACKOP555
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Make sure they are matches up. Your new connector is of quality and soldering or butt connect wires and crimp good. Then retest. Post. Back codes if issue remains.
Sep 29, 2025 at 5:48 PM
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STRAILER
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The wiring seems like it is shorting out when wrapped. I would double check your work, here is how the wires should go, also what are the code numbers so I can help fix that problem as well. Here are the wiring diagrams for the MAF sensor so you can make sure it is wiring correctly. Check out the images (below). Please upload pictures or videos in your response.
Sep 30, 2025 at 9:13 AM
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RLPETERSON
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Hi Ken, I'm getting code P0102 and P0133.

Roger
Sep 30, 2025 at 12:11 PM
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STRAILER
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So the first code can cause the second one, I would make sure the wiring is correct and solid. Next, check to make sure the intake boot does not have a crack and that it is tight on the throttle body, here is a video to help check for leaks:

https://www.youtube.com/watch?v=LRKWV4Are5c&t

Code P0102 - Mass Air Flow (MAF) Circuit Low Input

Code P0133 - O2 Sensor Circuit Slow Response (Bank 1, Sensor 1)

Please upload an image or short videos in your response of the problem, so we can see what's going on.
Oct 1, 2025 at 9:28 AM
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RLPETERSON
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Hey Ken,

I was waiting to get a sensor plug for my 2013 Toyota Corolla. I received it on Saturday. When I was installing it, I noticed that on the one that install before, the Brown and White wire was in number 3 position and the black in position 2; different from the wiring diagram. I thought maybe that I may have installed it so I wired the way in the wiring diagram that you sent. I started the car and the engine light came on, but this time I am getting a P0103 and a P0133. So is the wires in the diagram you sent wrong?

Roger
Oct 5, 2025 at 2:52 PM
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STRAILER
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I double checked the wiring diagram and it is correct. Can you upload an image of the wiring and connector so I can see it to be sure? Also, make sure there is not a leak between the MAF sensor and throttle body.
Oct 7, 2025 at 10:58 AM
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RLPETERSON
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Hi Ken,

This is the third Mass flow sensor connecter that I have put in the car. The wires are so far back from the connector that I can't show you a photo or them close to the connector. But I have wired it according to the wiring diagram that you sent me using shrink wrap connectors containing solder in the middle making sure to connect the wires tightly together.

I have attached a video of my smoke machine attached to the engine which shows that there aren't any holes between the throttle body and the MAS airflow sensor. However I have seen smoke coming out or where the engine filter is, could this be a problem?

Before I stated doing this the car was running fine. Now the engine is running rough and I am getting codes of P0103 and P0133. What could be the problem?

Roger
Oct 15, 2025 at 1:30 PM
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STRAILER
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I noticed the MAF is old, did you replace it? Also, can you confirm the code is a P0103 or P0102?
Oct 16, 2025 at 11:53 AM
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RLPETERSON
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Hi Ken,

The MAF sensor is new, I installed it about a month ago.

I have attached three photos. I have four P0103 and one P0133.
Oct 16, 2025 at 1:42 PM
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STRAILER
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Yep, all point to the wiring being not correct or you have a shorted out PCM. Also, use a flashlight to see if you can see the small numbers on the connector or sensor, I see the there are two black wires, only one of them (middle #3) should have power when the key is on (12 volts).
Oct 17, 2025 at 4:35 PM
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RLPETERSON
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Hi Steve,

I was able to get a OEM Mass Airflow sensor and 5 wires to replace the lines to the connector. The car is running now fine. But I recently got PO455 and PO441 coded. I was able to clear them. But I am wondering what could be causing them. I checked the gas cap and it was fine. I did some research and it pointed to the Evap Purge control valve. Do you agree with that assessment?
Nov 4, 2025 at 5:54 PM
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STRAILER
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We are glad you got the MAF sensor problem fixed! These are EVAP system codes please start a new thread for this issue. Post your new question here, you must be logged in.

https://www.2carpros.com/questions/new

Cheers, Ken
Nov 6, 2025 at 8:51 AM