P0171 P0174 Code - How to Replace MAF Sensor 1997-2005 Lexus GS300

Hey, everyone. Sue here from 1A Auto. Today we have an '01 Lexus GS300 in the shop. We're going to talk about code PO171 or PO174. One of the top common problems with Toyota Lexus is those codes. Quick fix, instead of paying big money, one of the top problems is the mass airflow sensor with that code. I have a new one I'm going to put in. I'm going to show you, and I'm going to show you the old one, compare it to you, show how dirty they get and why they set the code.

First, I'm going to show you the location of the mass airflow sensor. That is always usually near the airbox on the air tube that goes in to the throttle body. We have the connector right here. I'm just going to push down on that tab and pull it off. Always check for conditions of the tab. Make sure you don't have a burnt electrode or a wire problem. In this case there's nothing discolored. It looks pretty good. The code was a code PO171.

This original factory one has mounting screws that are Phillips heads. We're going to take that off, just by using a Phillips screwdriver, backing out on the two mounting bolts. Then just wiggle and slide it up. It has an O-ring on it. That O-ring is torn. You want no air going in there. We'll set a code. But this mass airflow sensor almost looks original.

If you can look in here, there's a wire right there. That wire picks up the reading. Look how dirty it is in this side. It almost looks like it has grease on it. So there--we're not getting the proper variables. It's not reaching in between the reading that it should be to give a good running condition. I'm going to put that aside, and then I'm going to grab a new one that I just ordered from 1A Auto. They're identical. See the clean one? Now you can see the difference. Look at that electrode. Wow.

Comes with a new seal. It also comes with a new mounting hardware. These are tempered torques. If you have brass inserts, this one does not, I have to use the old screws again. We give you a torque spit, tempered torque spit with two mounting screws, if you have the brass insert. If you don't, you can reuse the old hardware.

First thing I'm going to do is line that up, wiggle it down, and make sure that seal sits in there. I'll grab the two screws. Place them in and I'll take my Phillips screwdriver and tighten that down. Just get them started, and then I will tighten them both down. Once again, it's plastic, so we don't need to really crank down on it, but you want it tight. You don't want any air seeping through that seal. Reconnect it. Take your little code reader from 1A Auto, clear your code, and then go for a road test.

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