Code E034, Mass Airflow Sensor Circuit: Notes

The Mass Airflow (MAF) sensor measures the flow of air which passes through it in a given time. The ECM uses this information to monitor the operating condition of the engine for fuel delivery calculations. 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 sensor can be diagnosed using the procedures in this chart. Code E034 will set, when either of the following sets of conditions exists:

Engine running.
No MAF sensor signal for 250 milliseconds
Above conditions for greater than 4 seconds

NOTE: Test numbers refer to test numbers on diagnostic chart.

Test Number 1) This step checks to see if ECM recognizes a problem.

Test Number 2) A voltage reading at sensor harness connector terminal A of less than 4 volts, or greater than 6 volts, indicates a fault in circuit No. 492 or poor connections.

Test Number 3) Verifies that both ignition voltage and a good ground circuit are available.