MIL Mass Air Sensor-Bonneville

Low input voltage is the voltage going in:

So I would check the relay, the wire and connector at the sensor. Check the manual to see which is the input, and take a voltage measurement with the key on, and then put a fan forcing air into it, to see the voltage change.

The sensor reads the amperage needed to keep the wire heated to a specific temperature, when air passes it. Better yet, a square wave meter or lab scope would be far more accurate. (Before SPX/Sperry-OTC bought out TIF, they used to make a square wave counter for a digital VOM) I think they still do.

Otherwise, you'll have to buy an OTC or Snap On Vantage if you want to read square waves. For the do it yourselfer, voltage readings IE. voltage drop or amperage is fine.

Refinish King