Please advise what these codes mean... I think its a vacuum leak but I can't seem to find the problem. I am hoping this helps me narrow down my search.

P0171
P0174

Thanks!

 

P0171 = System too lean (Bank 1)
P0174 = System too lean (Bank 2)

From the factory service manual, the possible causes are (note that some items listed are for rich codes more than lean codes):
For lean and rich DTCs:

• Fuel system
• Excessive fuel pressure.
• Leaking/contaminated fuel injectors.
• Leaking fuel pressure regulator.
• Low fuel pressure or running out of fuel.
• Vapor recovery system.
• Induction system:
  • Air leaks after the MAF.
  • Vacuum Leaks.
  • PCV system.
  • Improperly seated engine oil dipstick.
• EGR system:
  • Leaking gasket.
  • Stuck EGR valve.
  • Leaking diaphragm or EVR.
• Base Engine:
  • Oil overfill.
  • Cam timing.
  • Cylinder compression.
  • Exhaust leaks before or near the HO2Ss.

Since you have a code for both banks, I'd suggest you focus first on systems that would effect both cylinder banks such as the PCV elbow and vacuum leaks. Intake manifold gaskets are also pretty common issues for either of these codes, but not usually at the same time.


-Rod

 

Thanks... I appreciate the response. Not to long ago I change the cam position sensor (diagnosed with codes) which made a huge improvement. It ran well for a few months then started acting up with the current CE light and a little bogging down here and there. I will go through the list you provided and see if I can narrow it down to something. Will update accordingly.

 

Well we did a little poking around under the hood and it looks like the pcv wasn't fully seated. We pushed it in, cleared the codes, and took it in for emissions testing. Aside from having to drive it a bit to reload the catalytic converter data, it seemed to do fine. So its good for another two years anyway. If this pops up again I suppose we will revisit. Stupid little stuff.

 

Great, I hope that takes care of it. Thank you for following up!

-Rod