VSsc400

iTrader: (1)

i have a 99 AWD with 99600 miles and it was throwing a CEL P0171

went to

I've cleaned the MAF sensor 3 or 4 times and reset the fuse #13 and it would come back after 40+ miles. I've looked in to see if an oxygen sensor or an Air Fuel ratio sensor could be cleaned.

I simply could not believe that so many air fuel ratio sensors could fail (many many rx300 have this issue).

If you look at the angle the sensor bank 1 sensor 1, it is positioned so that mousture would gather, thus promoting carbon deposit build up thus the sensor getting clogged and it appearing to have failed. Well the sensor is still good. it just needed cleaning.

1. I loosened the bolt clamp at the flex arm of the air intake
2. I opened the airbox
3. turn the airbox so you have a clear view of the intake
4. turn your car on
5. spray carb cleaner into the intake for 1 second. (your engine is going to act like it's going to stall out) wait 5 seconds.
6. repeat step 5, 10 times
7. press the accelerator to 3000rpm for 5 seconds and rest for 2 seconds and repeat once more.
8. repeat step 6 and 7, 2 more times
9. shut off car
10. remove fuse #13 and also remove the fuse right next to it(i'll check on the fuse number and name tomorrow) and wait 1 minute and put them both back in. If your mpg/avg speed readings have not reset to 0 then you have to do it again.

I have since driven over 1000 miles with no CEL coming back.

I hope this works for others. $255 is too much to pay for a sensor.

lexena

This is an excellent post. All Lexus and Toyota have this problem.

Lil4X

Nice work! Thanks for the tip.