Question 4Runner 2000 V6 P0171 code

[carlosgv1]

Hi, I have a 4 Runner 2 wd, auto. the check engine light coming on and installed the scanner, code P0171, I change O2 sensor bank 1 sensor 1 (OEM), fuel filter, sparks plugs(NGK), clean MAF sensor, no vaccum leaks. 5 miles after CEL on P0171.
I suspect bad MAF sensor, How I can inspection or check the MAF sensor resistance or volatage.
Please any advice.

Best regards.

[Flashgordon]

To properly read a MAF you need a scanner, which it sounds like you have. This will provide you with voltages (V) at different RPM's. Can't remember your exact MAF sensor wiring but you have 12v reference, ground and the signal wire....maybe a fourth but not sure. The signal wire should read about .9v to 1.2v at idle.
While your scanner is hooked up, pay close attention to the fuel trim values.
You might have a vacuum leak which can cause a code that looks like a bad O2 sensor.
Hope this helped.