P0171 on BANK 1 ONLY - What should I look at?

Question

2004 ford freestar 4.2 - P0171 (bank 1) - fuel trim seems normal on 2 (Short-term 1.5 at idle, 3.9 at 2500 RPM - Long-term 17 at idle, 14 @2500 RPM), on Bank 1 short-term reads 5.9(-) at idle AND at 2500 RPM. Long-term reads 25(-) at idle and 24(-) at 2500. What to look for?

Answer 1

P0171 Fuel trim lean Bank 1

Vacuum leaks, look for vacuum leaks, especially at the PCV hose.

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Vacuum leaks are the most common cause for a leak code condition, look at the PCV hose, and the vacuum hoses especially at the intake manifold