New Previa SC Oxygen Sensors Chasing P0171 Fuel System Lean Check Engine Light Solution

Previa SC LE AllTrac has been throwing a P0171 Fuel System Lean check engine light (CEL / DTC) every 50 to 400+ miles after I changed the head gasket - see the "Previa Mayhem" series of videos on the Head Gasket, Water Pump, Oil Pump Seals replacements.

I have now installed new Upstream and Downstream Oxygen Sensors. While the fuel economy is slightly improved and the Previa seems to be running much smoother, I am still seeing a return of the P0171 Fuel System Lean DTC.

This video shows the process of replacing both oxygen sensors as well as a quick repair for the Oil Pressure Sensor.

Let me know your thoughts for the ongoing P0171 Fuel System Lean DTC - I am not locating any vacuum leaks over the past few weeks and now driving over 2,000 miles since the head gasket replacement. I am now thinking it is fuel related - possibly the original fuel injectors at nearly 300k miles and 30 years or possibly just the fuel injector o-rings (I didn't replace the originals when I reinstalled the fuel rail on the head gasket replacement.

Thumbnail Title: Previa SC P0171
Car: 1994 Toyota Previa LE SC AllTrac

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