Mass Air Flow (MAF) Sensor -G70-, Checking

Mass Air Flow (MAF) sensor -G70, checking

Requirements
- Coolant temperature at least 80 ° C (175 ° F)
- Electrical consumers switched off (radiator fan must not run during test)
- A/C switched off
- Fuse for mass air flow sensor OK

Checking function
- Connect Vehicle Diagnostic, Testing and Information System VAS5051 or VAG 1551 Scan Tool and select engine electronics control module by entering address word "01", [1][2]Scan Tool Connecting and Initial Checks. When doing this the engine must be idle.

Indicated on display


Rapid data transfer HELP
Select function XX


- Press buttons -0- and -4- to select function "Basic Setting" and confirm entry with -Q- button.

NOTE: During the basic setting the engine control module closes the EVAP canister purge regulator valve -N80 and switches off the A/C compressor.

Indicated on display


System in Basic Setting Q
Input display group number XXX


- Press buttons -0-, -0- and -2- to select "display group number 002" and confirm entry with -Q- button.

Indicated on display


System in basic setting 2 ->
1 2 3 4


- Check displayed specified values for engine load.







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







Reading Display Group 002







Checking voltage supply to Mass Air Flow (MAF) sensor
- Disconnect harness connector from Mass Air Flow (MAF) sensor.







- Connect multimeter (voltage measurement range) between engine Ground (GND) and socket 2 of connector.
- Operate starter briefly.
Specification: approx. battery voltage


NOTE: The air mass meter receives its voltage supply via the fuel pump relay.


If the reading does not match the battery voltage:

- Check for open circuit or short to Ground (GND) in wiring between fuel pump relay and socket 2 on connector via fuse. Repair if necessary.

If specification is met:
- Check Ground (GND) connection from control module.

Checking Ground (GND) connection







- Connect multimeter (voltage measurement range) between sockets 2 and 3 of connector.
- Operate starter briefly.
Specification: approx. battery voltage


NOTE: Socket 3 on the connector is the Ground (GND) connection from the engine control module.


If the specification is not attained:
- Check wiring.







- Connect multimeter (voltage measurement range) between sockets 3 and 4 of connector.
- Switch ignition on.
Specification: approx. 5 V

If the specification is not attained:
- Check wiring.

Checking wiring for Mass Air Flow (MAF) sensor


NOTE: The wiring test includes also testing the signal wire.


- Connect VAG 1598/31 test box to wiring harness for engine control module. DO NOT connect to the engine control module itself, Connecting VAG 1598/31 Test Box







- Check for open circuit and short to B+ or Ground (GND) in the following wiring connections:

Connector for MAF VAG 1598/31 test
sensor -G70, socket box socket
3 27
4 53
5 (signal wire) 29

Resistance in wiring: max. 1.5 ohms

- Correct short circuit or open circuit if necessary.
- Also check for short circuits between all wires.

Connector for MAF VAG 1598/31 test
sensor -G70, socket box socket
3 53 and 29
4 27 and 29
5 (signal wire) 27 and 53

Specification: infinity ohms (open circuit)

- If wiring and voltage supply are OK, replace Mass Air Flow (MAF) sensor -G70.
- Display readiness code, Readiness Code Reading. Readiness code must be generated if DTC memory was erased, Readiness Code, Generating