The service engine soon light came on today when I was driving to work on my 2001 F150 4x4 Screw. I didn't notice ant difference in the way the truck was driving. I stopped by the local auto parts store & had them read the codes. 171 & 174 are the codes that came out.

I just did a tune up on it a couple of months ago. Replaced the COP, Spark Plugs, PCV Valve, Fuel Filter & Fuel Pump with all New Motorcraft Parts. Cleaned the MAF Sensor & IAC Valve.

What do you guys recommend checking for the lean codes? I've read that PCV Valve Hose cracks & will cause these codes. Any advice would be great.

Thanks!

 

Well, go check those parts....

There are already hundreds of posts about that code pair. Think yours is much different?

 

PCV elbow behind the throttle body is the most common vacuum leak.

 

Yup, very different...