Faulty can mean just not reading the air flow as accurately as the oem set up. The engine demand and air flow reading must match with 10% or better*.............. to feel right.......not throw codes.

If you install something that upsets the oem MAF calibration. the ecu hiccups.............not that you are really changing air flow very much just that MAF thinks you have.

It is not Infiniti's fault that your changes affect the MAF.

However we must determine if there might be a general MAF problem and only Infiniti knows the failure rate on unmodified cars!

* At each rpm and throttle position [load factor] there is some correct air flow [that varies with air temperature barometer and humidity]...........in order for the cats to work the AF must be accurate within +- 3% at cruise or idle.

The MAF reports a value and the O2 check the outcome, if the adaptive learn gets out of bounds [+- 10%] it throws a code.