There is already one DIY on this but I figured since I was going to clean it today I might as well make a DIY. If this is not needed moderators/admin's please feel free to delete the DIY.
Tool's Needed:
1. Screwdriver (Philips in my case) Some other RX's that I've seen have had allen key screw so check yours to be sure.
2. Mass Air Flow Sensor Cleaner.

1. First start by located the MAF sensor it is located on the air filter box.
2. Remove the connector from the MAF sensor. ( I removed this first because it was a little tight to remove but you can remove it after removing the two screws if thats easier)
3. Now remove the two screw holding the MAF sensor in place.
4. Remove the MAF sensor from air filter box.

 

5. Clean the red diode from both sides. One side of it will look much darker and will have dirt and other dust particles and the other side should look red but may also be a little dirty. Now spay this red diode with the MAF spray, till both sides look red.
6. Now look at the MAF sensor from the top and you will see that there are two little "lines" inside you want to spray that with MAF spray as well and then let the MAF sensor dry for a few minutes.
(Optional: Meanwhile as it is drying you can take this time to check the condition of your air filter.
7. Once the MAF sensor is dry place it back into the air filter box.
8. Now go ahead and secure the MAF sensor with the screws you removed earlier.
9. Reconnect the connector.
10. Now you can do one of two things either pull the 20a fuse labled efi for about a minute or disconnect the battery for a few minutes this will result in the ECU having to regather new data.

 

Hypervish - The MAF Cleaner you used (I bought it) says specifically NOT to use it on Karmen Vortex MAF's, e.g. Most Lexus Vehicles. What say you?

 

The can says to not use it on "most" Lexus vehicles, they don't specify which ones... This MAF sensor in particular will NOT be damaged using this specific MAF Cleaner, the reason I say this so confidently is since I've used it in two different RX's and one highlander. (they have the same part number, so I suppose it's the same MAF sensor)

Never the less if anyone feels uncomfortable using it, you can also use Electronics cleaner.

 

Fair enough. Thanks for the response.

Mine was fairly dirty on the one side as indicated by your DIY. I thoroughly hosed her off with the cleaner, and now the sensor is spic and span. We'll see how she does driving later this week.

Nice job on the DIY.

JBL

 

RX300 does not use the Karmen Vortex type MAF, you're fine.

 

No problem. Thanks, this was my first time making a photo diy, hopefully I'll be making more in the near future.

 

Looks like hot wire type MAF sensor. The karman vector does not disrupt airflow by design and looks like ours does (somewhat) so MAF cleaner should be safe...

Ref: http://www.autoshop101.com/forms/h34.pdf

 

CRC MAF Cleaner is the stuff I use

 

I took out the MAF sensor as described in your DIY.

The diode was completely black on one side and slightly brown on the other side.

I used the same MAF cleaner as you did.(the can in the photo above)
The black gunk was washed off the diode. However, no matter how
much I cleaned, the diode still looked brown. (like tea) Does the
diode really look red when new? This is the original MAF sensor
on my RX300 with 150,000 miles... perhaps time for a new sensor?

 

It's kind of a dark red even after cleaning, even when new from what I recall. Note that i can get chipped a bit from small particles over time (and I would know since I don't run an air filter on mine). Plus, I have been on my second MAF since December 2007.

 

no air filter at all?

(1)
what does the engine sound like?

(2)
isn't that bad for the engine?


By the way, my check engline light came on and AutoZone checked the codes for me. P0174 and P0171.
First thing I did was use the MAF cleaner and cleaned the sensor. I disconnected the battery to reset it.
The check-engine light hasn't come back yet. Can a dirty MAF sensor really cause P0174 & P0171 codes?

I know this is going to sound stupid, but how can my MAF sensor get dirty if I frequently change my
air filters?(with genuine Toyota air filters, every 6 months or so)

Thanks!

 

Yea I was wondering the same thing...maximum air is good, but the consequences of no air filter can be rather bad???

 

It depend on how you have the air intake system setup. Right now, there is no ram air system that sucks up air from outside the engine (like my bullhorn). When I set one up again soon, there will be an air filter. Thus it's not sucking up particles from elsewhere.

The engine gets loud under acceleration.

 

I just got a P0171, P0125, P1133, and P1135. Could this DIY fix the P0171? 3.5 years ago, the P0171 popped up along with P4050, and it cost me $190 to replace the MAF sensor and $300 in labor (3 hours ). I'm hoping I can do this myself, but I am not really knowledgeable. I was able to do the IACV clean up with no problem, and if cleaning/replacing the MAF sensor is as easy, I think I'll be in good shape and save some serious cash.

I'm in the process of purchasing the OBD-II scanner/reader and the CRC MAF sensor cleaner from Amazon in preparation for this DIY, but I want to make sure I'm headed in the right direction. Can I please get some advice? I have some questions as well:

1. I believe the OBD-II can reset the codes... Should I reset before or after cleaning the MAF? I thought I read somewhere that I should see if the same codes could pop up again after a reset.

2. After I cleaned the MAF, and I'm still getting the P0171 code, do I go straight to replacing it, or do I need to do something else?

3. I'm guessing the cracked exhaust manifold and/or missing air filter (in the glove compartment) could cause this?

4. How long can I drive my car around with these codes? I just got the code yesterday. I drive maybe 25-35 minutes total per day.

5. Anyway to fix the other codes myself? Or is this something that requires taking it to the shop?

Sorry for the thread hijack. I appreciate any advice and help! Thank you!

Edit: I just found a DIY for test/replacing the A/F sensors, if I do this as well, would that get rid of all the codes? Or is there more that needs to be done?

Edit 2: Let me elaborate - please tell me if I have this correct:

P0171 = MAF sensor needs to be cleaned/replaced to fix code.
P1133 and P1135 = Bank 1 Sensor 1 needs to be replaced. Replacing one sensor will fix both codes.
P0125 = ???