# failed emissions



## CSUdad1 (Feb 19, 2019)

Hi, my daughters 09 Murano was purchased from a private party here in Colorado a couple months ago. Seemingly no problems whatsoever. The car wouldn't pass emissions with a code indicating it needed an 02 sensor, bank 2 sensor 2. So I had that replaced....with labor nearly $400. Check engine light still appeared so I took to a local mechanic where they fixed another issue but wouldn't get into the sensor issues. $300 bucks. Now, after being checked again at AutoZone, I forget the actual code, but suggested taking the air intake off and replacing. I've looked for holes in the intake. I have no idea what else to do. If even professional mechanics can't figure it out. All the while I can't get the car registered. Any advice would be greatly appreciated. thanks,

Chris


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## rogoman (Dec 16, 2004)

For us to help you, you'll need to perform an ECU code readout AGAIN with a portable scan tool to see what fault codes are set. This is something you could do yourself with a portable scan code reader. The tool can be purchased at most auto parts stores or you can just go back to AutoZone to have them do it. Post the ACTUAL CODES here on the forum so that we may be able to help you further. If there is one or more fault codes set, they can help point to the malfunction. The codes are in the form as: PXXXX where XXXX is a numeric value; for example P0001.

There many folks here on the forum who are excellent mechanics, several are or have been Nissan trained so I'm sure we can get an answer for you.


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## CSUdad1 (Feb 19, 2019)

thank you. I have the latest code. its P0171.


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## K in Iowa (Jun 23, 2015)

P0171 indicates a lean mixture detected in bank 1. That is less than the optimal 14.7:1 air fuel mixture.

To keep the engine running properly, the engine computer tries to compensate for the lean condition by injecting more fuel to the mixture in an effort to maintain the proper 14.7:1 air to fuel ratio. When these adjustments become too large, code P0171 is triggered.

This is a fairly common code on the Murano, and may be due to any of the following:

O2 sensor 
Leak in the air intake, or a leaking vacuum line.
A dirty or weak mass air flow sensor.
A weak fuel injector.
And a couple of other issues that I forget right now. 

An air intake, or vacuum leak can sometimes be heard with the engine running. It will be a hissing sound, and frankly might be difficult to hear over the engine.

HOWEVER, I have fixed more than one P0171 error codes by cleaning the mass air flow sensor. It's a fairly simple task and the sensor is easily accessible in the air intake. 

If I were you, I would get a can of Mass air flow sensor cleaner and clean the sensor. It's just a spray can you spray on the inside of the sensor. You can google it's location. You'll have to remove a clamp on the air intake to expose the sensor. When you are cleaning it, don't touch the tiny wires that are across the air path. They won't hurt you, but you don't want skin oils to get on them.

While this may turn out not to be your issue, it's cheap and easy to try. I ended up cleaning the MAF on my 09 Murano at every other oil change just to avoid this code.

K


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## CSUdad1 (Feb 19, 2019)

I appreciate your help! Wow. Thank you. I will do what you suggested tomorrow. It's been excruciatingly frustrating!

Chris


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