check engine light 2 error codes

[spike1965]

My check engine light came on and the two error codes are P0171 and P0174. Its a 2003 Sport Xlt 4.0l.
Looking up the codes they are bank 1 and bank 2 running lean.
There are no vacuum leaks, so is it O2 sensor, cat converter, mass air flow?
Anyone else had this issue before?

 

[swshawaii]

The usual suspect. Inspect the PCV elbow underside closely.

P0171 & P0174 4.0L SOHC's 2001-03 Sport & 2001-05 Sport Trac.
http://www.explorerforum.com/forums/showthread.php?t=314670

 

[ccm2001]

I have the exact same model. And had those codes. Check the pcv elbow closest to your throttle body. Replace it and reset the codes

 

[koda2000]

if you don't find any other sources of vacuum leaks, it could be time to replace your upper/lower intake manifold O-rings/gaskets. another common problem with the SOHC engine.

 

[Tbruz]

X3 on the PCV elbow as the leading culprit.
Tbruz

 

[spike1965]

Thanks, will check out the pcv valve today