Air Flow Meter/Sensor: Testing and Inspection
NOTE:
- To functionally check the Mass Air Flow (MAF) sensor
- Component locations, refer to "Component Overview - II", Locations
Checking voltage supply
- Mass Air Flow (MAF) sensor fuse OK
- Disconnect MAF sensor harness connector.
- Switch multimeter (Fluke 83 or equivalent) to measure voltage and connect between connector terminals 2 (GND) and 3 (B+) using jumper wires from connector test kit VW 1594.
- Switch ignition ON.
Specified value: approx. 12 to 14 volts
If the specified value is not obtained, perform the following tests:
- Check Mass Air Flow (MAF) sensor fuse.
- Check wiring for continuity between terminal 3 and fuse using wiring diagram.
Specified value: max. 0.5 ohms (ohms)
- Check wiring for continuity between terminal 2 and intake manifold Ground (GND).
Specified value: max. 0.5 ohms
Checking signal wire
- Connect VAG 1598/19 test box to ECM harness connector.
- Check signal wire for continuity between MAF sensor connector terminal 1 and test box socket A12.
Specified value: max.1.0 ohms
If the specified value is not obtained:
- Find short circuit or open circuit; repair as necessary.
MAF sensor connector ECM connector A
terminal terminal
1 A12
NOTE: If it becomes necessary to repair or replace any of the Mass Air Flow (MAF) sensor electrical terminals, ONLY replace with gold-plated terminals
Checking function
- Slide back protective boot from back of MAF sensor connector (leaving it connected).
NOTE: The connector pin numbers are marked on the back of the connector itself.
- Switch multimeter (Fluke 83 or equivalent) to measure voltage and connect between terminal 2 (GND) and terminal 1 (B+) using jumper wires from connector test kit VW 1594.
- Switch ignition ON.
Specified value: 0.3 to 1.1 volts
- Start engine and let idle.
- Switch off all electrical consumers (engine coolant fan should not run during measurement).
Continuously vary engine speed between idle and 4000 RPM.
Specified value: 1.5 volts minimum to 3.4 volts max. depending on engine speed (RPM)
If the specified value is not obtained:
- Replace Mass Air Flow (MAF) sensor.