Mass Air Flow 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 VAG1551 scan tool and select engine electronics control module by entering address word "01". Connecting VAS 5051 Scan Tool
When doing this the engine must be at 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 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 air mass meter
- Disconnect harness connector from air mass meter.







- Connect hand-held 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 hand-held 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 hand-held 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 sensor


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


- Connect VAG1598/31 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 VAG1598/31 test box,
MAF sensor -G70,
socket
3 27
4 53
5 (signal wire) 29

Resistance in wiring: max. 1.5 Ohms

- Repair short circuit or open circuit if necessary.

- Also check for short circuits between all wires.

Connector for VAG1598/31 test box
MAF sensor -G70,
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. The readiness code must be regenerated if the DTC memory was erased.
Readiness Code Checking
Readiness Code, Generating