What really is PO138?

Question

I have read forums saying to change oxygen sensors. Other forums say just to remove mass airflow sensor, spray it down with CRC mass airflow cleaner, dry it and then replace it, should fix the problem. So, which is it really?

Answer 1

It depends what the exact problem is its possible its either one or both are bad.
Try to clean the mass air flow sensor first with Mass air flow sensor cleaner.

reset the light and see if that fixes it, if not replace the oxygen sensor.