Code 48, Mass Airflow Sensor: Notes

Mass airflow meter measures amount of induction airflow. This information is used by PCM to determine adjustments to air/fuel ratio. MAF sensor is a hot-wire type. Sensor maintains hot wire at a predetermined temperature. The greater the airflow across the hot wire, the more current is required to maintain hot wire temperature. Sensor changes the current requirements into a frequency signal which is read by the PCM. The PCM calculates airflow based upon this signal.

1. Determines if fault is a hard failure or an intermittent condition.
2. Checks for 5-volt reference from PCM.
3. Verifies both ignition voltage and a good ground circuit are available.