Loss of Power and/or Check Engine Light With Code P0171 and/or P0174 on Infiniti QX4

Problem Description and Possible Solution

The mass airflow sensor may fail resulting in a loss of power and/or Check Engine Light illumination with code P0171 and/or P0174 stored. Our technicians recommend replacing the failed airflow sensor to correct this concern.

Problem Data
RepairPal Verified
Average mileage: 140,000 (140,000–140,000)
3 model years affected: 1999, 2000, 2001
4 people reported this problem
Viewing 1 - 2 of 2 comments
My qx4 is not give me a power its take time to give a power if i press the gas i loss the power if i alwys stop irs take time to give a power again what is the problem of my qx4 pls help me
Check Engine Light with Codes P0171 and P0174.... I bought it used with these codes, got it from a friend and the car ran okay...Not as much acceleration as I thought it should have, and the gas mileage was pretty lousy... However, I am a broke musician, so of course I just kept driving it as it was (for another year or so). Finally, things deteriorated to the point where it would stutter or hesitate when I tried to accelerate, and it absolutely SUCKED at trying to go up any incline at all. After reading something about this topic, I unplugged the power to the MAF sensor, to see if the car would run better...and it did....(as long as I never got the RPMs past 2200-2300!) Of course, this means I have to crawl away from red lights and stop signs, AND I have a top speed of about 65...(which PISSES other drivers off, by the way).... So, me being the typical broke (and lazy) musician, I continued to limp around town like this for about 4-5 months. All the research I did indicated that at the very least, I would spend 300-400 bucks just to see if the sensor fixed the problem... Well, I finally found a MAF sensor for about 40 dollars (new, with a 1yr Warranty!), so it is on the way... I'll update you all when it arrives....
I replaced the Mass Air Flow Sensor with a really inexpensive one (under $40 ordered from, and "VROOM!"...the car runs great! Took 2 minutes to replace! VERY happy dude! Palmettojeff at yahoo dot com if you have any other questions....
Good Luck,
Charleston, SC