I have a 2007 SE with about 134,000 miles. My car is throwing P0171 and P0174, lean bank 1 and 2. I recently had the coils and plugs replaced. After replacing, I had a bad #5 coil, so I swapped this with an original and my car ran great for a few months, before throwing the above codes last week. Searching the forum seems to suggest an intake leak somewhere, or replacing the MAF, which I don't necessarily have an issue doing, but I don't want to start throwing hundreds of dollars at this issue if it won't fix it. I have a Fujita CAI, Cattman y-pipe, and Magnaflow exhaust with resonator. Can some of you experts recommend some things I can check to try to get rid of this code? Thanks in advance for the help.

 

If it was only one of the codes by itself, I'd say replace the O2 sensor. But both banks at the same time make me lean towards the MAF.

 

do the smoke test to see if you have an intake leak. Sounds like an intake leak to me. The MAF going bad is not common on this car. It wouldn't hurt to clean it though. Here check out this video if you are not sure how to do a smoke test, it gives you an idea of what is needed. https://www.youtube.com/watch?v=zMok2y05jNE. If you use an e-cig, you might be able to do the same process as this guy. There are other ways, just search the net.
Also this is the stuff to clean your MAF. http://www.autozone.com/miscellaneou...cleaner/36011/.
Just make sure the cleaner is specific for the MAF, it is expensive and can easily get damaged.

 

Thanks for the insight, I'm not the most mechanically inclined so was wondering how I can check for intake leaks. I recently bought an OBD II scan tool which displays live data on the car, does anyone have a resource I can use to see what the settings should read on this live data, I haven't been able to find it anywhere? I'd like to check the O2 sensor voltage, MAF levels, etc to see if I can narrow the issue down at all. Any help is appreciated. Thanks.

 

Still trying to diagnose the issue, but realized that I made a really bone headed mistake that could be contributing or causing this. I have the Fujita intake, and I used the K&N cleaning kit, and proceeded to oil the filter after I cleaned it, which I'm realized now was really stupid. So without making me feel any worse, do you think this could be causing too much air to enter the engine and causing the lean conditions? My long term fuel trim numbers per my scan tool have been upwards of 30%, while the short term numbers seem fine to my untrained eye. Any help is appreciated.