# Testing a MAF



## OhmsLaw (Mar 29, 2016)

I haven't had to do this yet so I welcome reasons why this may not work. Objections are more informative than agreements.

You need a source of moving air: a vacuum cleaner, or hair dryer with the heat "off". 
For on-vehicle testing, a cardboard baffle will separate ingoing air from outgoing air as long as the MAF doesn't care about air direction.

The vehicle schematic may tell you what is +12v, gnd, and signal out.

The signal out reading should change when going from no air movement to full blast.
No change almost certainly means bad MAF.
Change may still mean bad MAF.


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