This pic shows the position of the Mass Air Flow sensor (on my ZD30) on the top of the air filter housing. Shown here with the wiring cover removed.
The testing procedure is done at the back of the plug with suitable probes to interrogate the wiring. The main test is for battery voltage at terminal 4 and supply voltage (5volts) at terminal 2 (white wire). Then you should have 1.6 – 2.0 volts at the red wire of terminal 1 with the engine idling. Voltage will increase as engine revs increase.
To remove the sensor you will need a T20 torx bit. After removing the two retaining screws, gently twist the sensor and remove from housing.
To clean the MAF sensor you will need a suitable cleaner, I got CRC MAF cleaner from Repco, I had to ask for it, it wasn't on display.
Do not touch any of the surfaces of the sensor, let the cleaning spray do the work. If you work over a white cloth, you can see the color of the solvent coming off, keep going untill the solvent comes off clean.
This pic shows the sensor cleaner, the sensor removed from the housing, and the torx bit used to remove it.
If you do need to replace the MAF sensor, these are the part numbers to use. These numbers are just for the sensor shown in the photo above. This is significantly cheaper than replacing the WHOLE air flow meter, housing and all.
ZD 30 Series 1-3 22680AD21A (previously 22680AD210 which was before that 22680 AD201)
ZD30 Series 4 22680 7S000
Tony