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Bull6791

P0171 Code

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Thursday driving to work I got a CEL. CEL stayed on until Saturday until my boss brought his code reader in to work.

He put his AUTOXRAY code reader on car. It said no emissions codes but 1 code. He pulled the code. The code was p0171 SYSTEM TWO LEAN BANK 1.

He cleared the CEL at noon Saturday and it had been off ever since.

Before, during and after the CEL the car is running great. No idle issues. No RPM issues.

 

Is this a fluke or not

My guess is the INTAKE MANIFOLD GASKET or VACUUM LEAKS.

How do you prove if it is the INTAKE GASKET.

How do you check for VACUUM LEAKS.

 

Thanks

Frank

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P0171 usually is not a "fluke" code, though, the issue can be quite elusive and the code may not return for months or even years. Lots of possible things could cause that code to pop up - though vacuum leaks are by far the most likely suspect. Some of the other possibilities are listed below:

 

- induction system leak (vacuum leak)

- leak in exhaust system (leak close to sensors)

- faulty O2 sensor (remember yours is a AFR not a conventional O2 sensor, ie. $$$)

- ignition misfire

- faulty injectors

- faulty fuel pump

- faulty MAF sensor

 

This has been talked about pretty extensively on this forum - just search the term "intake manifold gasket" for some diagnostic, troubleshooting steps.

 

As for it being the intake manifold gasket - possible. You can opt to test this through diagnostics, or some people just change it outright.

 

You're car is a later model 9th gen Corolla - so you would already have the newer gasket on it. Doesn't mean that the gasket cannot fail. Those composite intake manifolds can distort slightly, causing the gasket to prematurely fail. Not a whole lot you can do about it, just the nature of the system.

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Fish

My corolla is a 2005. I am not sure but I think I have old INTAKE GASKET.

I want to check gasket before I say it is bad. I will have to search forum for diagnostics.

How do I check for VACUUM LEAKS.

Especially items on your list.

The code reader says NO Emissions codes.

Thanks.

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Opps - I thought you had the 2007 - got your two cars mixed up.

 

You can check with the gasket on the car - but most opted to just peel it off and just change it. You'll do all the work to get to the gasket, at that point, might as well change it.

 

Lots of ways to check for vacuum leaks - just do a search. If you need more help - there are a number of videos floating around out there.

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Fish

I thought faulty o2 sensor, ignition misfire, faulty injectors and faulty mass air flow sensor all have their own code. So if it was one of these issues you would get a different code.

Fish does my 2005 corolla have the old black intake gasket. What year did they start putting the new orange one in the corolla

I thought to check vacuum leaks you spray water on vacuum lines with engine running and if idle changes you found the leak.

How do you check for leak in exhaust system close to sensor.

Thanks

Frank

Edited by Bull6791

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They never did switch to orange silicone gasket # 17171-22060. It was only related to the TSB. Black gasket part # 17171-22030 was replaced by # 17171-0D020... If yours has the original black gasket, it most likely is leaking and causing your P0171 code. Just replace it with revised orange silicone gasket # 17171-22060 or Victor Reinz # MS19590. You'll see evidence of it leaking if you look beside gasket where it sits on engine head. More easily inspected with plastic engine cover removed.

 

http://www.toyotapart.com/M.I.L._ON_DTC_P0171,_AND_OR_PO133_ENGINE_RUNNING_LEAN_IN_SUBFREEZING_AMBIENT_TEMPERATURES_T-EG045-07.pdf

 

http://www.toyomotorparts.com/parts/toyota-17171-22060_gasket-intake-manif.html

 

http://www.rockauto.com/catalog/x,carcode,1433059,parttype,5424

 

http://www.toyotanation.com/forum/132-9th-gen-corolla-1st-gen-matrix-2003-2008/410129-diy-2005-2008-corolla-matrix-pontiac-vibe-intake-gasket-replacement-pics.html

 

 

Leaks on exhaust can be heard or felt by hand. They leave blown black carbon evidence. They normally occur at the exhaust manifold flange gasket (donut). I upgraded mine to a FelPro # 61106.

Edited by dom

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Like I said but I do not know I though Faulty o2 sensor,ignition misfire,faulty injectors, faulty MAF sensor and faulty fuel pump all would throw off their own code.

So if these things throw off their own code how can it be these items when I get a P0171 code.

 

Also if I spray water on vacuum lines with engine running and idle changes is that how to check vacuum leaks.

Also since my 2005 should have black intake gasket their is no way to check it. I should just replace it.

Thanks.

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Those can throw off very specific codes, but issues with those systems "can" also cause a lean-mix DTC. That's why it is important to "diagnose" a CEL -too often a technician will look up the code and tell you XXX part is bad. Any tech that does that is not doing their job properly.

 

Just pull the intake off and have a look. Like I mentioned, by the time you get down to inspecting it - might as well change it.

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Fish

I totally agree with you VACUUM LEAKS are buy far the most likely suspect of CODE P0171.

I want to check for VACUUM LEAKS but I do not know how to do it.

Let me know if this: from what I read you spray water on vacuum hoses with engine running. If you hear a change in idle that is where the VACUUM LEAK IS.

 

FISH I should probably Change out the intake gasket like you said. I have an 05 corolla it probably has the old black gasket. I should upgrade to new orange gasket.

Thanks.

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Lots of ways to check for leaks - the one you mentioned works, as long as the fluid is able to be pulled into the leak. Sometimes you have to add a couple drops of detergent to help the water "wet" the surface.

 

Some people like to use solvents, but with so much plastic under the hood - I'm really reluctant to recommend that option.

 

They also make special leak checking machine - usually only available at shops. There are some that you can buy for DIY - but the amount of training needed to accurately use these, probably not a good fit for most people.

 

Just do a search online - on this forum and other forums. Everyone has their own take on how to check for leaks.

 

But like dom mentioned in other posts - this is a pretty common issue on the 9th gen Corollas - might be further ahead to just change out the gasket. At least that way, you know that you have a solid intake gasket on there and can rule that out from the diagnostic process.

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Without pulling the code - that would be a VERY difficult diagnosis, sometimes impossible. The CEL will help point you in the right direction, then you can start the process of elimination to diagnose the CEL. Swapping parts can help in some cases - but in the end, this is a losing proposition, especially to your wallet.

 

Much of this also depends on what CEL was thrown up. Some certain DTCs are very powertrain and/or model specific. That's why sometimes, one has to take the car to the dealership - as some independents don't have the knowledge or information to diagnose a problem. Even worse would be your chain shops - they can only pull up info on their database and have to be dependent on their technicians.

 

That's why forums like these are around - lots of personal input from many different owners, each sharing some of their experience. Ex: The case of the P0171 code on a 9th gen Corolla - that is a well known issue - enough owners have brought this up with their service technicians that Toyota release a TSB (technical service bulletin) to help diagnose the problem.

 

Keep in mind that it is entirely possible that your gasket is fine - but given the number of cases of warped gaskets on the 9th gen - statistically, when you have a P0171 code pop up, it would likely be related to a vacuum leak from the intake manifold, especially the gasket. It is a low cost, fairly easy DIY project - this would be one of those times where swapping the part would be OK. If it doesn't fix it - you can rule out the gasket as a culprit, and go from there (assuming you installed the gasket correctly).

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Fish

Did you ever hear of AUTOXRAY CODE READERS most people that I work with have them.

Also how is the code reader part of ULTRA GUAGE.

Thanks. Like I said I just wanted to know the right way to Handel diagnostic codes in the future. Since I am new to this it is easy to get code and keep changing part till I hit the right on. Which is wrong thing to do.

Thanks.

Edited by Bull6791

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There are no codes for faulty injectors or fuel pump, nor is there a fuel pressure sensor... A quick look at the edge of your intake manifold gasket where it sits on engine head would confirm right away that the gasket is in fact leaking, by the visible dark blow-by residue. Replace with gasket # 17171-22060 and be done with it.

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