Mass Air Flow (MAF) Sensor, Checking - Bosch

Voltage Supply For Mass Air Flow (MAF) Sensor, Checking (Bosch MAF Sensor)







- Disconnect connector from Mass Air Flow (MAF) sensor.
- Connect multimeter to terminal 2 of connector and engine Ground (GND) for voltage measurement.
- Operate starter briefly.
Specification: approx. battery voltage


NOTE: Voltage is supplied to Mass Air Flow (MAF) sensor from Fuel Pump (FP) relay.


If there is no battery voltage.
- Check wire connection from terminal 2 of connector to Fuel Pump (FP) relay via fuse for open circuit and short circuit to Ground (GND), repair if necessary.
- Connect multimeter to terminal 2 and terminal 3 of connector for voltage measurement.
- Operate starter briefly.
Specification: approx. battery voltage


NOTE: Ground (GND) from the ECM is present at terminal 3 of connector.


If specified value is not obtained, check wire connections.
- Connect multimeter to terminal 3 and terminal 4 of connector for voltage measurement.
- Switch ignition on.
Specification: approx. 5 volts.
If specified value is not obtained, check wire connections.

Wire Connections For Mass Air Flow (MAF) Sensor, Checking (Bosch MAF Sensor)


NOTE: Signal wire is also checked during wire test.


- Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks" Testing and Inspection







The following wire connections must be checked for short circuit to B+, Ground (GND) and for open circuit

Connector for VAG1598/31
-G70 Mass Air FLOW test box terminal
(MAF) sensor
2 27
4 53
5 29
5 29

Wire resistance: max: 1.5 Ohm
- Also check all wires for short circuit to each other.

Specification: infinite Ohms (no continuity)
- If the voltage supply and the wire connection are OK, replace Mass Air Flow (MAF) sensor -G70-.

Display Group 002:

If the specification is obtained:

- Press -> button.
- Press buttons -0- and -6- to select function "End Output" and confirm entry with -Q- button.
- Switch ignition off.

Reading Display Group 002

Display Field 3:

Display Field 4: