Code 31, Mass Airflow Sensor, Short Circuit: Notes

The Mass Airflow (MAF) sensor measures air flow passing through it in a given time. The ECM uses this information to monitor operating condition of the engine in calculating fuel delivery. A large quantity of air movement indicates acceleration, while a small quantity indicates deceleration or idle.

The MAF sensor produces a frequency signal, which cannot be easily measured. Sensor can be diagnosed using the procedures on this chart.

The MAF sensor also contains the fuel control switch, which provides the ground to the circuit opening relay to operate the fuel pump once engine has started.

1. Verifies B+ and ground to MAF sensor.
2. Verifies proper voltage control to ECM from MAF sensor.