My check engine light came on today. I ran the ob2 scanner and it came up with P0171 which means the (system too lean, bank 1) I guess it was the MAF sensor so i cleaned that all up. I guess the next try is the O2 sensor. Anyone else have a suggestion?

thanks

toyota tacoma SR-5, 5 speed manual trans, 2wd

I think you are on the right track with the MAF sensor. Make sure you reset your CEL after you cleaned the MAF sensor.

If you get another CEL, let us know.

hupptoy

Yes, the front O2 sensor would be the next likely culprit.

I'm dealing with the same thing and The past owner of mine had a K&N filter inplace and after reading some good posts here I started by switching air filters to a standard for now. Then although I had already spent a finger on a O2 sensor I took some advice and went after the MAF. Advance Auto had eletronics cleaner and MAF SENSOR CLEANER. Although the forum said I could use Electronics cleaner I spent the extra $2 for the MAF Cleaner because I've also heard that the MAF sensor is pretty salty to replace. IIcould see oil in the bottom of the sensor staw...hmmm.
I was keeping track of my milage because it went from 300 per tank down to 250 and now isn't the time for poor milage. Unfortunately I was at a half tank when I unhooked my battery to reset the CEL (not sure how to do properly) and it clear my trip milage...bummer. So I have to Start over at $2.57 a gallon to see if things have improved.
I'd appreciate any feed back and I'll try to keep you posted of the results.

I also just battled the same problem. I changed the MAF and put a stock type filter back in. The problem ended up being just an air leak between the MAF and the throttle body. I put a hose clamp on the fitting coming out the back side of the tube just before the throttle body and the CEL went away... or it burned out. Also to clear the CEL all you need to do is pull the EFI fuse out.

Actually, the PO171 code should clear itself after a couple of drive cycles. So if you're worried about pulling cables or wondering which fuse to pull, all you have to do is drive the thing (I think 2 driving cycles clears the code, IF t's gone).
Look for air intake leaks (as stated above), and clean the MAF really well. The O2 sensor is expensive, and many times isn't the problem; all it's doing is reporting that there is a discrepancy between what the engine THINKS it is burning, and what's ACTUALLY getting down the exhaust pipe.

I wonder if my 99 v6 3.4l is also experiencing an air intake leak. I just had the P0171 codes show up. I took it to the dealer and they had me replace the MAF. This cleared the code. The truck was running great (quick and responsive) for a few days after the MAF was replaced, but then went back to running sluggish. The code has not come up but the truck just doesn't feel the same. Feels likes I've always got to be hard on the gas. Could this be caused by an air intake leak? Any thoughts?