Question

I got the engine code P0171 on my 2001 Toyota Corolla. Replaced OEM MAS Sensor, O2 Sensor, Fuel Pump and Filter, Spark Plugs, Air Filter, can't find exhaust or intake leak. Checked injector inlets. Replaced ECM. I'm stumped.

Answer 1

You have replaced everything, I guess the only thing left is the replace the engine coolant temp sensor, if there is no wiring issue.

 

Answer 2

P0171 Toyota Code - Fuel Trim System Too Lean Bank 1
Read more: https://www.autocodes.com/p0171_toyota.html