How to fix error code

My check engine light came on and I read the code as PO 171, SYSTEM TOO LEAN: BANK 2. I can not find any where in my service manual on how to correct this problem. Any suggestions?

Thanks

I had a lean problem found debris in vac lines from dpfe sensor to exhaust ports. These were the chrome lines that come up from the driver side manifold. I also ended up changing the egr valve that was my final fix.