Code 31, Mass Airflow Sensor Circuit Shorted Circuit VIN 5): Notes

The Mass Airflow (MAF) sensor measures air passing through it in a given time. The ECM uses this information to monitor engine operating condition 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. The MAF sensor also contains the Manifold Air Temperature (MAT) sensor and provides ground to the circuit opening relay to run fuel pump once engine has started.

1. Verifies B+ and ground at MAF sensor.
2. Verifies proper voltage control to ECM from MAP sensor.
3. Verifies proper voltage from MAF sensor with engine RPM.