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Ivan Alvarez
Ivan Alvarez,
Category: Infiniti
Satisfied Customers: 111
Experience:  lead technician at Performance Tire and Automotive
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I have a 2008 Infiniti M45x with 107k miles on it, and it is

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I have a 2008 Infiniti M45x with 107k miles on it, and it is throwing code P0174 twice, and giving me horrible gas mileage. I have cleared codes after cleaning the MAF sensor, and replacing intake air filter, but the code is still pending even though the SES light hasn't come back. My mechanic checked all sensors, all areas for vacuum leaks and was unable to find any issues with any of the recommended trouble areas. We are both at a loss. Any ideas what else could be the issue? fuel fulter/pump? catalytic converter?
JA: Does the engine stall right after starting? And what about hesitation or jerking during acceleration?
Customer: no stalling or harsh idling. it does hesitate very slightly from time to time, but I don't drive it that often.
JA: Are you fixing your M45x yourself? What have you tried so far?
Customer: so far I replaced intake air filter, and cleaned MAF sensor. my mechanic has checked for vacuum leaks and any faulty sensors like the O2 sensor. So far nothing seems to be malfunctioning and there are no leaks.
JA: Anything else you want the mechanic to know before I connect you?
Customer: i'm a novice DIY person so I won't be making the repairs myself, I just wanted to get an idea on what the issue could be besides the issues i've troubleshooted already. Thanks

Another thing to look at would be exhaust leaks around the 02 sensor on bank 2. If it was a bad maf it would be also giving you a p0171. Also check the pcv system for vacuum leaks.

Bank 2 is the passengers side.

Customer: replied 1 month ago.
Thanks, ***** ***** to mention that originally it did throw P0171, but after I cleaned the MAF sensor, the code didnt come back.

Ok I would double check the exhaust leaks then since the only code to return is the p0174.

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