Diagnose shows PO171 or PO174. What is the most likely problem?

What is your question?

What is the likely problem and how expensive is the repair? I have never used repairpal before and have no pass word for repairpal, and therefore have had difficulty submitting my question.

What makes this problem better or worse?

More often in warm weather

How long has your 2009 Lexus LS460 had this problem?

A few months, but getting more often