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Discussion Starter #1
Please Help Me What Does This Mean.....2011 Odyssey EX-L....Big Or Small Repair...Easy Fix???

Thanks In Advance
 

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Woah! Slow down there folks. A DTC does NOT tell you what part to change. Rreplacing an O2 sensor is just a guess and may be a total waste of money. P0171 means the computer is correcting for a lean condition on bank 1 (the rear bank.) A lean condition can be caused by any number of things. It could be a vacuum leak, it could be a Mass airflow sensor, it could be low fuel pressure, it could be lots of things.

We need a lot more info. What kind of miles on the van? Are there any other codes besides P0171? It will take a scan tool and looking at some live data to determine the issue and why it's running lean. If you don't have that capability then I'd recommend getting a diagnostic done on it BEFORE replacing ANYTHING. Often times parts are replaced, that don't need replacing, and end up getting replaced with low quality and even non-working aftermarket parts, causing the issue to get worse before getting better.
 

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I see you're in NYC. There's a guy on Staten Island who runs a diagnostic business called New Level Auto. He has a YouTube channel but runs a legitimate diagnostic business. I don't know what he charges but he is one of the best. Pay him, or someone like him, to diagnose it and then do what he recommends.
 

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With that kind of mileage my first guess would not be an O2 sensor. It very well could be but that's not the first guess. Have you done spark plugs on this van? They were due at 105K along with your timing belt service.

The first thing I'd do with this vehicle is plug in a scan tool and take a look at fuel trims to see the extent of the lean condition and see if it's happening on the other bank but just not to the extent of setting a code or if the problem is really localized to bank 1.

There's just a lot more to it than throwing an O2 sensor at it. Besides, if you're going to throw an O2 at it you might as well throw both upstream and downstream O2 on that bank at it since both contribute to fuel strategy on these vans. I would also check the intake tube that goes from the air filter box to the intake manifold. I've seen jiffy lube places leave those loose and cause lean conditions.
 

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Does your scan tool display live data? I'd like to know what the short term fuel trim (STFT) and long term fuel trim (LTFT) numbers are at idle and at 3000 RPM.
 

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Discussion Starter #11
With that kind of mileage my first guess would not be an O2 sensor. It very well could be but that's not the first guess. Have you done spark plugs on this van? They were due at 105K along with your timing belt service.

The first thing I'd do with this vehicle is plug in a scan tool and take a look at fuel trims to see the extent of the lean condition and see if it's happening on the other bank but just not to the extent of setting a code or if the problem is really localized to bank 1.

There's just a lot more to it than throwing an O2 sensor at it. Besides, if you're going to throw an O2 at it you might as well throw both upstream and downstream O2 on that bank at it since both contribute to fuel strategy on these vans. I would also check the intake tube that goes from the air filter box to the intake manifold. I've seen jiffy lube places leave those loose and cause lean conditions.
ok will check this weekend
 

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Ah The O2 Sensors,....Lovely....Thnaks Guys I'll Start With That
O2 sensors are the 2nd sensors on the cats, this code is coming from the air fuel ratio sensor.

Thoroughly diagnose the problem before you replace the sensor. Lean condition can be a lot of things. I would check the intake system first, check the intake tube. (airbox to throttle body)
 

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Woah! Slow down there folks. A DTC does NOT tell you what part to change. Rreplacing an O2 sensor is just a guess and may be a total waste of money. P0171 means the computer is correcting for a lean condition on bank 1 (the rear bank.) A lean condition can be caused by any number of things. It could be a vacuum leak, it could be a Mass airflow sensor, it could be low fuel pressure, it could be lots of things.

We need a lot more info. What kind of miles on the van? Are there any other codes besides P0171? It will take a scan tool and looking at some live data to determine the issue and why it's running lean. If you don't have that capability then I'd recommend getting a diagnostic done on it BEFORE replacing ANYTHING. Often times parts are replaced, that don't need replacing, and end up getting replaced with low quality and even non-working aftermarket parts, causing the issue to get worse before getting better.
^+1. Replace with OEM parts, not the random stuff you see at the stores and online. Denso is the OEM part for the exhaust sensors. Like John said, thoroughly diagnose the problem first.
 

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O2 sensors are the 2nd sensors on the cats, this code is coming from the air fuel ratio sensor.

Thoroughly diagnose the problem before you replace the sensor. Lean condition can be a lot of things. I would check the intake system first, check the intake tube. (airbox to throttle body)
This code could come from the downstream sensor or the upstream sensor since both contribute to fuel trims. The code could also come from a vacuum leak such as a torn or loose intake boot. The code sets when the computer has to add more than a specified percentage of fuel to keep the engine in stoichiometric.
 

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...The code sets when the computer has to add more than a specified percentage of fuel to keep the engine in stoichiometric.
when that happens, For my body
It's time to add more tequila
 

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I had the same problem in my girlfriends Chevy Cruze the other day. I added some redline fuel cleaner a week or so earlier and on her second tank of regular gas it threw a code, obviously the computers are pretty sensitive and try to adjust the fuel air trim ratios etc on the fly and sometimes they can get out of whack.

It might be something quite small please keep us posted.
 

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Discussion Starter #18
Well I Cleared The Code And The Light Hasn't Come On Since,..I think It's Because Of The Damp Weather And Not Giving The Car A Chance To Rest Before Starting It Up
 

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Well I Cleared The Code And The Light Hasn't Come On Since,..I think It's Because Of The Damp Weather And Not Giving The Car A Chance To Rest Before Starting It Up
Probably will come back soon or later.
 
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