Mass Air flow issues?

Tiny
RLPETERSON
  • MEMBER
  • 2013 TOYOTA COROLLA
  • 4 CYL
  • 2WD
  • MANUAL
  • 175,515 MILES
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?
Monday, September 29th, 2025 AT 12:39 PM

12 Replies

Tiny
BLACKOP555
  • MECHANIC
  • 10,386 POSTS
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.
Was this
answer
helpful?
Yes
No
Monday, September 29th, 2025 AT 5:48 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
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.
Image (Click to make bigger)
Thumb
Was this
answer
helpful?
Yes
No
Tuesday, September 30th, 2025 AT 9:13 AM
Tiny
RLPETERSON
  • MEMBER
  • 14 POSTS
Hi Ken, I'm getting code P0102 and P0133.

Roger
Was this
answer
helpful?
Yes
No
Tuesday, September 30th, 2025 AT 12:11 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
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.
Was this
answer
helpful?
Yes
No
Wednesday, October 1st, 2025 AT 9:28 AM
Tiny
RLPETERSON
  • MEMBER
  • 14 POSTS
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
Was this
answer
helpful?
Yes
No
Sunday, October 5th, 2025 AT 2:52 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
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.
Was this
answer
helpful?
Yes
No
Tuesday, October 7th, 2025 AT 10:58 AM
Tiny
RLPETERSON
  • MEMBER
  • 14 POSTS
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
Video (Click to make bigger)
Thumb
Was this
answer
helpful?
Yes
No
Wednesday, October 15th, 2025 AT 1:30 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
I noticed the MAF is old, did you replace it? Also, can you confirm the code is a P0103 or P0102?
Was this
answer
helpful?
Yes
No
Thursday, October 16th, 2025 AT 11:53 AM
Tiny
RLPETERSON
  • MEMBER
  • 14 POSTS
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.
Images (Click to make bigger)
Thumb
Thumb
Thumb
Was this
answer
helpful?
Yes
No
Thursday, October 16th, 2025 AT 1:42 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
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).
Was this
answer
helpful?
Yes
No
Friday, October 17th, 2025 AT 4:35 PM
Tiny
RLPETERSON
  • MEMBER
  • 14 POSTS
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?
Was this
answer
helpful?
Yes
No
Tuesday, November 4th, 2025 AT 5:54 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
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
Was this
answer
helpful?
Yes
No
Thursday, November 6th, 2025 AT 8:51 AM

Please login or register to post a reply.

Related Mass Air Flow Sensor Replace/Remove Content

Mass Air Flow Sensor Replacement
GUIDE
Mass Air Flow Sensor Replacement
After starting the engine post sensor replacement, the sensor instantly calibrates itself so there is no learn time required. This sensor is subject to debris and ...
VIEW MORE