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.