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Discussion Starter #1
Hey everyone I am new to this forum. I am having lots of problem with my 2001 is300. First my CEL light came on. I ran the scanner and came up with to codes. P0171 and P0174. Which is for the o2 sensor. I replace both of the and still the light came back on. Now they are four codes P0171 twice and P0174 twice. I did a search on the forum and some people have the same problem but different codes. Some people change the MAF sensor but did'nt post back up the say if the problem was fixed. I am also having slow take of in 1st gear and sometime a jerk in 3rd gear.
Can someone please help me out.

thank you.
 

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Sounds like your throttle body needs to be cleaned out. the MAF sensor will cause all the problems you are describing. What you can do is either replace the MAF sensor, or attempt to clean it. Let me dig up some info on it for you in a PDF format. I will PM you with my findings.
 

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Also what O2 sensors did you replace? There are 3 in the car. 2 before the y pipe and one after the y pipe. I know its another stupid question but are the plugs securly fastened? I am only saying this because I had the same problem (on a different car) and the cable wasnt pushed in far enough
 

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Discussion Starter #4
abrx7 said:
Also what O2 sensors did you replace? There are 3 in the car. 2 before the y pipe and one after the y pipe. I know its another stupid question but are the plugs securly fastened? I am only saying this because I had the same problem (on a different car) and the cable wasnt pushed in far enough
I replace the first two before the y pipe. The plugs are securly fastened.
thank you.
 

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Well if you are still getting that code then I would say there is a high probability that the one after the y pipe is bad.
 

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Anthony Persaud said:
Hey everyone I am new to this forum. I am having lots of problem with my 2001 is300. First my CEL light came on. I ran the scanner and came up with to codes. P0171 and P0174. Which is for the o2 sensor. I replace both of the and still the light came back on. Now they are four codes P0171 twice and P0174 twice. I did a search on the forum and some people have the same problem but different codes. Some people change the MAF sensor but did'nt post back up the say if the problem was fixed. I am also having slow take of in 1st gear and sometime a jerk in 3rd gear.
Can someone please help me out.

thank you.

who told you that? You were screwed as far as diagnosis as soon as you started by having incorrect/incomplete information.

P0171/0174 are for A/F system too lean.
P0171=bank 1
po174=bank 2
This does not automaticly indicate a o2 sensor problem. More likly in fact it is a mass airflow sensor issue since it involves both banks.
Check tghe Mass airflow meter as it is almost always the culprit with these codes. probably dirty giving incorrect information.




(2 trip detection logic)<<<means its happened at least twice

 Air induction system
 Injector blockage
 Mass air flow meter
 Engine coolant temp. sensor
 Fuel pressure
 Gas leakage on exhaust
 Open or short in heated
sensor 1)
 Heated oxygen sensor
ECM
 PCV piping<<<loose or disconnected????
 

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remove it and inspect. if the two wires inside are filthy, clean it and reset the ECM. If they are spotless, troubleshoot the problem. Throwing parts at it will be very costly. Perhaps swap MAF's with another member for diagnosing the problem.
 

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Discussion Starter #13
Everytime disconnect the battery the car feels like its running on two cylinder after. Is the the right way to reset the ECM
 

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Discussion Starter #14
I removed the MAF and cleaned it using the MAF cleaner from Auto zone and also cleaned the throttle body, after reinstalling the MAF sensor I cleared the CEL using the pocket scaner. After about 45 mins of driving the CEL came back on. The car seems to be driving much better except for a little hesitation while switching through 1st and 2nd gear.
 

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Bank 1 sensor 2 O2 sensor

Take it to Toyota and they will fix it. Mine is in right now for CEL being on and they called and said it was the Bank 1 Sensor 2 O2 sensor.
$167.24 for the part and $254 labor. Rip off I know, but cheaper than the lexus dealer and the CEL will go away!
'01 with 64K miles.
 

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i just got back from the dealership this morning.. only had the car 10 days (2001 is300 w/64k miles) and the CEL came on the second day. since then it's been going on and off every few days, more often off. finally got it in today and luckily the light came on again while i was on my way down there. they said it was the heat oxygen sensor but couldn't find anything wrong with it and if it comes up again to try and take it to a lexus dealership. so for all the driving (dealership i bought from is 45 mins away) i got a 4 hour free carwash.. took em forever cuz they said they had to remove one of the seats to get to the sensor. hopefully they can get it fixed for good just because i get worried seeing the light on when i've only had the car such a short time. and it would be on the dealer's dime.
 

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Lextech Mentioned that A Gas Leak Could Be The Problem. I Have Two Exhaust Leaks Right Now. One Where The Exhaust Manifold Connects To The Down Pipe And One From The Down Pipe To The Resonator. It's All Megan Racing Exhaust System. I Just Changed The Gaskets But The Check Engine Light Still Came Back. Would Anyone Recommend Welding Those Locations Shut Or Does Anyone Have An Alternative Fix? And I'm Just Assuming That The Leaks Are The Cause Of My CEL.
 
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