Hey, this is my first post on here, although I've been searching around the forums for a while for answers to quick fixes.
About a week or two ago I put my cold air intake in my mustang. About 3-4 days ago I was kinda gunning it a bit, then I heard a slight sound come from the engine like it released something or depressurized, and then the check engine light came on. It also seems to be burning gas a lot quicker since this happened.
I brought it to autozone to get the code checked, and it came up as:
P0174 System Too Lean (Bank 2)
After reading on the forums here, I was thinking it might be a vacuum leak or a bad O2 sensor, but would those cause a drop in gas mileage too? My dad talked to some friends and he said that they said that it was the CAI itself, but I'm very doubtful of that.
I'm not gonna lie, I'm not exactly an engineer when it comes to cars, but I'm trying to learn more, any help is greatly appreciated.
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95 V6 Mustang, Since I got it: Cold air intake, stripes, halo headlights, soon exhaust/better wheels/a system
the computer will readjust itself with the kit on it. As for the O2 sensors, that can make the engine run richer or leaner. If the car still has the original ones on it, you can cleaned them off with carb cleaner or replace them. I installed a cold kit and my light never came on. I sprayed my O2 sensors (all 4 of them) and stopped using so much gas. Hope this helps. Also welcome and enjoy.
I just went through that same code on my 95. After receiving much help from this site, I found the problem to be the upstream O2 sensor on the driver side (bank 2). Let me point out that there is a list of problems that can cause this code. One of them is a vacuum leak, which I found and corrected one of those also. My post on this should be a page or so old. I titled it accordingly. My 3.8 has 178,475 on the clock, with the standard head problem done at 80,000. I went through most of the list of reasons due to my mileage. Check out the post,it has good info in it.
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1995 coupe, 5-speed, bright blue, black & grey interior, home made rear seat delete for the pooch, 180 degree thermostat, Billet quadrant, adjustable clutch cable, firewall cable adjuster, billet headlight knob, Cobra shift knob, Energy Suspension front sway bar bushings, plug and
play OEM fog lights and switch.
I did an edit on my previous response, but, it didn't add anything.
Page 5 is wher the post is on this topic, where I asked the same question...hope this helps.
Welcome to the site!!
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1995 coupe, 5-speed, bright blue, black & grey interior, home made rear seat delete for the pooch, 180 degree thermostat, Billet quadrant, adjustable clutch cable, firewall cable adjuster, billet headlight knob, Cobra shift knob, Energy Suspension front sway bar bushings, plug and
play OEM fog lights and switch.
After checking out my hoses I figured a few of them had leaks, went down to autozone and replaced one of them, other one is in a tighter spot I'll wait until tomorrow to get to.
Also cleaned my MAF sensor and got a fuel additive to clean the injectors, cleared the check engine light, and so far it seems like it's slightly more responsive and hasn't come back on yet. We'll see after driving on it for a few days if it comes back on or not.
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95 V6 Mustang, Since I got it: Cold air intake, stripes, halo headlights, soon exhaust/better wheels/a system
1995 Mustang Check Engline Light 
