DTC P0171, P0174: Fuel Trim System (RH) Too Lean; Fuel Trim System (LH) Too Lean: Notes

WARNING: This page is about a different car, the 2004 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: DTC P0171, P0174 Detection Condition & Possible Causes Chart

Courtesy of MAZDA MOTORS CORP.