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Discussion Starter #1
Hi
I have a 2001 toyota corolla with 107,000 miles on it.
The check engine light came on, so i took it to AutoZone and the error code i got from them was P0171 (system too lean)
What are the possible causes and how to fix it.
is it some thing serious, i drive 40 miles each way to work.
do i get it fixed as soon as possible

Ashish
 

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P0171 relates to a reading your oxygen sensor is picking up. The first thing you should check is the output voltage to make sure it is within specification. If the voltage is off, replace the O2 sensor in question.


 

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The fuel filter should be in-tank, and a hassle to get to. After 107K miles, it would be wiser and easier to change the 02 sensor first.
 

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Discussion Starter #5
the light is off again

Hi
it is very weird, but the light is off now, it comes on some times and then it is off again after i drive about 20 miles.
what do i do, do i still change O2 sensor, and change fuel filter
is there any think i can put in fuel to clean fuel system

Ashish
 

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OmarR said:
The fuel filter should be in-tank, and a hassle to get to. After 107K miles, it would be wiser and easier to change the 02 sensor first.
ashish it'd be best to clean the maf before buying anything. your symptoms sound identical to many that have had dirty maf sensors on their 01's so clean it. dont worry about fuel additives or fuel filters, thats not going to help with this problem, but you can buy chevron techron to clean your system out if you want.

PS: check my reply on the other forum that you posted this same question on. :naughty:
 

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BigWilly ;)
2001 Toyota Corolla
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had a system too lean code pulled from my 01 corolla LE

does your car have any hesitation? irratic idle?

if so it's probably a MAF sensor..
 

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btw I had niether of those symptoms when my maf sensor was faulty, yet fixing the problem has kept the c.e.l. away now for well over a year. :naughty:
 

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Discussion Starter #10
realistic said:
did you ever find out what the problem was? i am having the same issue with my 2001 corolla. an update would be awesome!
Seems there are issues with MAF sensor, i did change the air filter, and then tried to clean the MAF sensor using contact cleaner, but i guess it screwed up some thing and now i am getting P0300 code also, i am trying to find out how to check the ground circuit, and find out how to test it the MAF sensor is not working,
After that going to change my MAF sensor and see what happens

I dont know what the real issue is , but my car is giving my about 36 miles per gallon on highway so dont know what to make out of it, i read some where that if the MAF sensor or O2 sensor is faulty then the milage goes down..

Let me know if you are able to fix it, i will tell you if i am able to fix it

One thing for sure, iam trying to avoid going to dealer who charge way 2 much for it
 

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partznet.com had the best price I could find for the maf sensor, it was $128 shipped and I installed it myself. :naughty:
 

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Discussion Starter #12
HI
I was able to fix it by changing MAF sensor, and i also change O2 sensor, some how i am getting P0420 error code,
any ideas

Ashish
 

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The P0171 code that you are getting on your Corolla is caused by a bad mass air flow sensor, which can be found on the tube going to your air box, replacing the sensor and clearing the code will do the trick.:thumbup:
 

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P0171

Yeah, Hello,

I have replaced the MAF sensor on my 2001 Toyota Corolla, AND the O2 sensor AND all 4 ignition coils AND all four spark plugs AND I had it checked for vacuum leaks, none by the way, AND I am still popping a P0171!!! Now what next? Replacing the fuel injectors? Replacing the fuel pump? fuel screen? These Toyota Corollas are more expensive than they are worth I am starting to think.
 

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P0171

Yeah, Hello,

I have replaced the MAF sensor on my 2001 Toyota Corolla, AND the O2 sensor AND all 4 ignition coils AND all four spark plugs AND I had it checked for vacuum leaks, none by the way, AND I am still popping a P0171!!! Now what next? Replacing the fuel injectors? Replacing the fuel pump? fuel screen? These Toyota Corollas are more expensive than they are worth I am starting to think.


So what was your problem ? Did you figure it out? I also have a p0171 on my corolla with 197k
 

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This is an old thread. Please start a new thread. Thanks
 

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Try techron before you do anything else. First Echo I bought had 195k miles and P0171 code. A bottle of techron and it went away and did not come back in 30 k miles. You can pull the injectors, send them off to be cleaned and checked for good spray patterns and balanced volume of fuel delivered, but if you just got the code try the bottle of techron. Seen it clear up some really nasty injectors just fine.

This SHOULD be your first step in a diagnostic process, before turning any wrenches or you may find it is the LAST step in a very frustrating repair procedure, with many parts replaced that did not need replacing.

Check utube for videos of before and after cleaning and realize that any deficiency in spray pattern or volume of fuel delivered will trip the code P0171.
 
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