hi, had a code P0174. if left on without clearing, P0171 will join the code list. as you might have guessed. it could be 10things. 1st have it scanned. lean bank 1 & lean back 2. welldont buy anything, 1st check for vaccume leak. the power steering pump has a 2 vac. line switch. the line broke. dont start changed 02sensors, fuel injectors, etc... check for vac. :Dleak. also you might think you can hear the vac leak. Nope. hope it helps
gorilla

Correct. The P0174/P0171 codes (Fuel system too lean, banks 1 and 2) usually means a vacuum leak from the intake manifold gasket, a vacuum hose, PCV hose, etc, or the MAF is dirty, or there's a fuel delivery problem (clogged injectors, fuel pump going out, etc). Only after all those can be eliminated do you look at the fuel-air sensor(s).

Funny. Two weeks ago I got the P0174 code and a couple of people told me it was the O2 sensor(s). Before the O2 sensor arrived, I cleaned the MAF sensor and after 600 miles, no CEL yet.

I have A 00 tundra. I have been trouble shooting these two coeds for weeks on my own. P0174 & P0171 were the only 2 codes i had. I replaced ALL the O2 sensors. Nothing changed. I then thoroughly cleaned the Mass air flow sensor with MAF cleaner, let it air dry, then put it back in. DO NOT use canned air which could ruin the delicate wires. The ONLY symptom my truck was showing was a slightly lower than normal idle, everything else was fine, also i did not have any vac leaks. So i bought a brand new MAF and installed it and just like that, no more coeds and the truck returned to normal idle speed. So just because your truck doesn't have a rough idle, no power when gas is applied, harsh fuel economy, or any of those symptoms a bad MAF usually displays it could still be bad. Oh And also like many others out there i also have an after market cold air intake on my truck. Hope this helps many of you who are puzzled like i was.

tunda00 im having the same issue. i have a k&n air intake and i recently replaced the filter RF-1045 - K&N Universal Air Filters, Universal Air Filter direct from K&N (http://www.knfilters.com/search/product.aspx?Prod=RF-1045&cst=81515.1.000) and after installing CEL came on soon after. I've cleaned the MAF and checked for leaking hoses. Im just curious is the filter not as "thick" thus allowing more air to pass through it? Mine has been idling extremely low and sometimes when sittin at a light, I shift into neutral and get the RPM's up because I feel like it will stall on me (but that hasn't happened yet). Where did you get ur new MAF at??

How do you test a MAF sensor? The ECU has a code for it, but it appears it can malfunction without throwing the trouble code. I have MAF sensor 22204-0F010.

How do you test a MAF sensor? The ECU has a code for it, but it appears it can malfunction without throwing the trouble code. I have MAF sensor 22204-0F010.

;)
Part 1 -The Basics of Testing a MAF Sensor. (http://easyautodiagnostics.com/testing_maf_sensor/maf_sensor_testing_1.php)

;)
Part 1 -The Basics of Testing a MAF Sensor. (http://easyautodiagnostics.com/testing_maf_sensor/maf_sensor_testing_1.php)


Thanks for the reference!

tunda00 im having the same issue. i have a k&n air intake and i recently replaced the filter RF-1045 - K&N Universal Air Filters, Universal Air Filter direct from K&N (http://www.knfilters.com/search/product.aspx?Prod=RF-1045&cst=81515.1.000) and after installing CEL came on soon after. I've cleaned the MAF and checked for leaking hoses. Im just curious is the filter not as "thick" thus allowing more air to pass through it? Mine has been idling extremely low and sometimes when sittin at a light, I shift into neutral and get the RPM's up because I feel like it will stall on me (but that hasn't happened yet). Where did you get ur new MAF at??

This shows you exactly what the difference is between a filter that actually filters grime, dust, silicon, silt, etc and those that like to call themselves "free flowing".

If you stick your nose in a cloud of silt, what do you do? You sneeze, right? That's exactly what your truck is telling you.

Go back to an OEM or equivalent paper filter. It is more than adequate for your engine's needs. Your engine, and its oil volume will thank you in the long run.