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Engine check light: P0171

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Old 09-13-2004, 10:06 AM   #1
Nam
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Engine check light: P0171

Last labor day weekend, while towing a 16' boat to Fresno from Sacramento, CA, the engine check light came on. I still get 19MHP consistently with full load, three passengers, and towing the boat with camping gears on it.

Went home, checked out the code, it said P0171, system too lean (sp), I reset the ECU, for two days, the light hasn't come back on.

What could be the problem? any help is highly appreciated. Is it related to the MAF sensor? I hear that thing is very expensive.

I have 77K miles on the truck.

Thanks,

Nam
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Old 09-13-2004, 10:44 AM   #2
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it is indeed the MAF. you can clean it yourself and not get a whole new one.

or if you have a warranty/extended warranty, you can get it done free at the stealership.
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Old 09-13-2004, 12:14 PM   #3
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I didn't check, but if P0171 is the MAF, there ae plenty of write-ups in the tech section that you can use to do-it-yourself. If I have time, I (or someone else on the forum) will confirm the the code.
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Old 09-13-2004, 12:48 PM   #4
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Thanks Lee & Rick. I'll do the search.

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Old 09-13-2004, 12:49 PM   #5
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thats the code i got when it was my MAF.
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Old 09-13-2004, 12:57 PM   #6
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I got system too lean (bank 1) for P0171
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Old 09-13-2004, 05:10 PM   #7
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which is caused by a dirty MAF in that instance... as far as i know
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Old 09-13-2004, 05:55 PM   #8
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Thanks every one for your promptly replies. I've just finished cleaning the MAF sensor. It turns out to be a 10 min. job. I had to temporary relocated the cruise control module to gain better access...but very simple, quick, and easy!

Prior to this, I stopped by Lowes to pick up an "electrical connector cleaner" can, the sensor looks *very* dirty especially from the outer side (facing the airbox). Wish I had the camera handy so I could take some pics. Oh well...it's done.

Hopefully this will solve the supposed-to-be-costly problem.

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Old 09-13-2004, 06:35 PM   #9
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Yeah I got the same code at 75,000 miles after playing in some dirt one day. Unfortunatley, I had mine cleaned and it still didn't work. Had to replace it

Luckily though, the extended warranty covered it. I remember reading here somewhere that someone's dealer wouldn't cover MAF's under the extended warranty, but mine did
Oh well I won't complain
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Old 09-14-2004, 05:07 AM   #10
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you might be thinking of my thread, where i told them i had the warranty when i brought it in, they still charged me over 300 bucks. then i went back in after finding out it was supposed to be warrantied work.

dont worry, i got it all back.
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Old 09-14-2004, 05:08 AM   #11
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9 times out of 10 it is indeed the MAF causing that code...
If cleaning doesn't do the trick then it will need to be replaced (check junkyards too for parts)
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Old 09-14-2004, 08:00 AM   #12
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Pretacopower:: how much did it cost you for the sensor?

Lee:: lucky you...mine is out of warranty for a long time; however, I hope the cleaning trick will do it.

MTL_4runner:: Thanks for the info. I like your OBD II scan tool. I use the generic one which could only tell me the codes.

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Old 09-14-2004, 11:20 AM   #13
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Quote:
Originally Posted by Nam
Pretacopower:: how much did it cost you for the sensor?


Nam
Mine was covered under warranty, but I remember my local mechanic said it would cost me $250 installed (or somewhere around there).
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Old 09-14-2004, 03:26 PM   #14
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I got a used one for $150 from a junk yard. Worked great after I screwed the first one up.
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Old 09-17-2004, 12:40 PM   #15
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Quote:
Originally Posted by DavidA
I got a used one for $150 from a junk yard. Worked great after I screwed the first one up.
i just got mine too at a junk yard for $75. It came from a 2002 camry. they sell it at the dealer for $151 brand new. FYI, our MAF is the same as 98-03 sienna, 2002-04 camry, 2001-2 highlander, and the 1st gen RX300.
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Old 10-07-2004, 07:09 AM   #16
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Update!!!

After cleaning the MAF sensor, about two weeks later, the engine check light is back on...it went off for a day and came back on again. Checked out the code, it said P0171 again.

Time for a new sensor I guess!

IS3004Runner: thanks for the infor. if that is the case, I will try to swap mine with my dad's 2000 Sienna and see if it is going to solve the problem.

any other suggestions?

Nam
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Old 10-07-2004, 10:26 AM   #17
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Quote:
Originally Posted by Nam
Update!!!

After cleaning the MAF sensor, about two weeks later, the engine check light is back on...it went off for a day and came back on again. Checked out the code, it said P0171 again.

Time for a new sensor I guess!

IS3004Runner: thanks for the infor. if that is the case, I will try to swap mine with my dad's 2000 Sienna and see if it is going to solve the problem.

any other suggestions?

Nam
Nope, you definately need a new sensor....
Many have had good luck with getting a used one out of the junkyard too.
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Old 10-07-2004, 11:56 AM   #18
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Did you actually clean both hotwires, or just the obvious bulby thingy? With what cleaner?
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Old 10-07-2004, 12:04 PM   #19
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Quote:
Originally Posted by Unhappy99
Did you actually clean both hotwires, or just the obvious bulby thingy? With what cleaner?
No wires...I just cleaned the bulby thing with "Electrical Contact Cleaner" and couples of Q-tips.

One even that kind of noticable to me was that I flood the engine with water since the door lach of the air filter was open and I went through water without knowing it...it stalled the engine for a moment and it started right up. The air filter was soaked with water...

I am not sure if that would make the MAF sensor dirty or malfunction...I'll double check and see.

Last result, get a new sensor...thanks to Montreal_4Runner

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Old 10-07-2004, 12:05 PM   #20
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Quote:
Originally Posted by MTL_4runner
Nope, you definately need a new sensor....
Many have had good luck with getting a used one out of the junkyard too.
I will check local junk yard and see what they have. I don't think it's too hard to find.

Thanks,

Nam
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05, 1999, 2000, 4runner, air, c0de, circuit, fuel, metering, p0171, ratio, repair, rx300, sensor, sienna, toyota

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