2008 Toyota Corolla: P0171 code

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Old 01-18-20, 02:54 PM
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2008 Toyota Corolla: P0171 code

I have the following error in extreme cold weather. -35c I cleared it once and it came back as I felt it may have been a cold related issue

I visually checked the vacuum hoses and will clean the Maf and then reset the code. I am nervous using propane or a flammable liquid near the engine to a isolate any leak I may have missed with a visual check. I will try soapy water .

a rebuilt maf costs 100 bucks here so thatís an option if I feel itís the maf but after cleaning if the error does not go away I donít want to waste 100 if itís not the issue

intead there was a technical bulletin put out by today a for 2005 to 2008 vehicles related to a bad intake manifold gasket. I could attempt to replace it but itís not my preference unless I am certain that is the issue

just when meeting if anyone has advice or exposure to that specific vehicle and error

any advice would be appreciated
 

Last edited by PJmax; 01-18-20 at 04:12 PM. Reason: Title corrected
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Old 01-18-20, 03:01 PM
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Sorry it’s a 2008 Toyota Corolla, not that it would make a difference
 
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Old 01-18-20, 06:47 PM
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My experience with the PO171 code which shows “lean bank 1” (or some wording like that) :

I pulled the MAF sensor and sprayed with CRC MAF Sensor cleaner until the metal side shined like new chrome. Erased the code and it never came back.
On another vehicle I had to replace the upstream (first) oxygen sensor which is accessible from right under the hood.
There are a couple of very good YouTube videos that show what to do on both of the above.

I never used propane in diagnosing this code. I have heard and read that this could be a manifold gasket problem but have not come across it myself.
By the way, how many miles on this vehicle?
 
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Old 01-18-20, 07:42 PM
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There are 96 thousand miles on it

maf has not been replaced to my knowledge

I will definitely clean it with CRC maf spray and reset the code

tge tough decision will be to either spend the 100 to replace the maf or open up the intake manifold and replace the gasket

I do wonder about the cold weather either impacting the gasket or the maf sensor
 
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Old 01-19-20, 04:31 AM
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How did you arrive at MAF proiblem from that code?
MAF does not have gasket. Toyota MAF is very basic device, just 2 screws holding it in place on air intake. I have never ever heard of rebuilt MAF and they cost $60 plus new in store. Aftermarket, of course. There is nothing to rebuild there.
You have vac leak somewhere and should spot that.
Also, outside of that code, we really not seen any symptoms description in your post. In such cold, metal shriknks. Surely it could pop some gap somewhere open.
 
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Old 01-19-20, 07:38 AM
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P0171 is a system too lean code so either too much air or not enough gas. It’s a bad error because it can be caused by slot of issues including a bad intake manifold gasket as I read this vehicle and other 2005-2008 Corollas may suffer from.

I read it’s also a faulty or dirty MAF. I am in Canada. They go for 100 at NAPA here...and those are rebuilt ones.

I will try to clean my old maf with crc spray first and reset the code and hope that was the issue. I could not see any holes or cracks in the series of air hoses and tubes

i don’t have a smoke machine so it’s hard for me to guarantee I do t have a vacuum leak. I saw you tube videos where people use carb cleaner or propane air. Does anytime have a safer method of finding a vacuum leak?

it Could also be an 02 sensor but it seems like there is no perfect way of isolating exactly what causes it unless you clean maf, replace maf, look for vacuum leak, ....then replace O2 sensor? Or replace the intake manifold gasket?

it just seems like it’s a bit of a random search to fix this error code ?
 
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Old 01-19-20, 09:22 AM
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How can you rebuiuld a MAF? It's simple glass bulb with some minor electronics in it...
But whatever. rebuilt it is.
It is safe to use carb cleaner. Or, propane bottle. Nothing is going to explode. Go to Eric The Car Guy site, look up procedure.
O2 sensor can be easily scoped with multimeter.
You still did not post what exactly are the symptoms.
We all know what that code description is. MAF will give you very erratic, surging, sputtering engine run. Not just simple code presence.
 
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Old 01-19-20, 09:34 AM
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I am really curious, how can one rebuild a sealed plastic box with glass bulb on the side?

https://www.ebay.com/itm/OEM-22204-2....c100677.m4598
 
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Old 01-21-20, 10:42 AM
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I took out the MAF and it was spotless, the 2 small wires in the housing were very clean

i tested for vacuum leaks using water and didn’t detect anything

I reset the error code

the weather has warmed up from -30c and the error code has not returned

this may not mean The issue is gone away but I don’t really want to mess around with it unless I truly feel an issue real and not weather real acted. The car seems to idle just fine and the acceleration and gas mileage seem normal

i
 
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Old 01-23-20, 07:47 AM
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There is a TSB, for P0171 in cold weather. The fix is an updated intake gasket #17171-22060.
Could be it.

Google TSB EG045-07
 
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Old 01-23-20, 02:05 PM
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Yes I saw that. I think that is the issue as itís a known issue that impacts 2005-2008 corollas.

I am just trying to decide if I leave it given itís only an issue in extreme cold at this point vs tinkering with the intake manifold removal


the error has not returned since the extreme cold snap ended .... several days of -30 weather
 
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