# MAF sensor testing



## 2ks (Jun 27, 2009)

Anyone know how I can test the MAF sensor (4 pin). I don't have a Bentley manual yet, or VAG-COM. Wondering if there is a way using a multimeter on the harness either connected or not, ie: pin 4 should be 12v, pin 2 XX ohms, etc. CEL showing P0102, P0171, P0174. Sensor probably not working at all. Trying to find a good one now without paying a fortune, 220.00 at stealership. Just want to make I'm getting the right voltage etc. at the connector.


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## spitpilot (Feb 14, 2000)

*Re: MAF sensor testing (2ks)*

Here's what Bentley has to say about "Checking Voltage Supply @ MAF":
Disconnect connector, pin out is 1 2 3 4 5 with "1" being at the rounded end of connector. 
Let engine idle with connector off.measure volts between pin # 2 and ground....11-15 volts. If no volts..check wire conection from terminal 2 to Fuel Pump relay (J17)..see wiring diagram.
If voltage to #2 is OK...switch ignition on..measure vlots from pin #4 to ground...4.5-5.5 volts. If there is no voltage here..switch ignition off and check wires from ECU to the MAF connector...
pin 29 on ECU goes to MAF pin 5, ECU 53 goes MAF pin 4, ECU 27 goes to MAF pin 3...Max wire resistance between pins...1.5 ohm..with ECU and MAF disconnected check insulation resitance between wires to be sure there are no wire to wire shorts in harness....if all wires are OK and voltage supply checks out as above...time to replace MAF...but I'd clean it first with "electronic parts cleaner spray"...Electra Cleen by CRC Chemical or simiilar product...spray both sides of MAF..DO NOT TOUCH sensor with anything or blow it with compressed air to dry..let dry by just sitting there. The sensor is a thin film unit and very delicate! Good luck! http://****************.com/smile/emthup.gif


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## Slimjimmn (Apr 8, 2006)

*Re: MAF sensor testing (2ks)*

with the vag com read ecm mvb 32. The reading is normal +/- 5%. If its -25% or +25% its either a large vacuum leak or a bad maf. Also check mvb 3 or 5 for the maf sensor Gm/s reading. Spec at idle is 2.5-3.8gm/s if its higher say 8 than its either a vacuum leak or bad maf.


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## 2ks (Jun 27, 2009)

*Re: MAF sensor testing (Slimjimmn)*

Thanks slimjimmn will keep this thread for when i get VAG-COM access. Tested with multimeter and all seems good on the car side, new MAF be here in a day or so.


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