My car sprung a
P0101 pending code recently, which shows up as a
Mass or Volume Air Flow Sensor "A" Circuit Range/Performance on my BlueDriver OBDII scanner. I started to read this article SUCCESSFUL MAF SENSOR DIAGNOSIS by Sam Bell and I couldn't follow this discussion that uses the terms open-loop and closed-loop. What exactly is this referring to and how can I trigger each in my vehicle?
To function correctly, all of the air entering an engine's combustion chambers must be "seen" by the MAF sensor. This means that any vacuum or air leak downstream of the sensor will result in insufficient fuel metering, causing a lean condition in open-loop operation and higher-than-normal fuel trim values in closed-loop.