Download Mass Air Flow Sensor, Checking

Mass Air Flow Sensor, Checking
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Mass Air Flow Sensor, Checking
Special tools and workshop equipment required
Multimeter -VAG1526- or multimeter -VAG1715Connector test kit -VAG1594-
Wiring diagram
Test requirements
The respective fuse of Mass Air Flow (MAF)
Sensor -G70- must be OK: → Wiring
diagrams, Troubleshooting & Component
locations
Battery voltage must be at least 11.5 volts.
All electrical consumers such as lights and rear
window defroster must be switched off.
Parking brake must be engaged or else
daylight driving lights will be switched on.
For vehicles with automatic transmission,
selector lever must be in P.
If vehicle is equipped with an A/C system, it
must be switched off.
Ground (GND) connections between engine
and chassis must be OK.
Coolant temperature must be at least 80° C
→ Chapter, Diagnostic mode 1: Check
measured values; PID 5, Coolant temperature.
Vehicles from 09.99
Fuel Pump (FP) Relay -J17- must be OK,
check: → Wiring diagrams, Troubleshooting &
Component locations
Function test
– Connect diagnostic tester → Chapter.
– Start engine and let run at idle.
– Under address word 33, select “Diagnostic
mode 1: Checking measured values.”
– Select the measuring value “PID 16: Air flow
quantity at Mass Air Flow (MAF) sensor”.
– Check specified value of air flow quantity at
Mass Air Flow (MAF) Sensor at idle:
PID
Diagnostic text
16:
Air flow quantity at
Mass Air Flow (MAF)
sensor
Engine running at
idle
Vehicles ► 08.99
Specified value:
3.00 to 4.00 g/sec
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Mass Air Flow Sensor, Checking
Vehicles 09.99 ►
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2.00 to 5.00 g/sec
– End diagnosis and switch ignition off.
If specified value is obtained, but DTC memory has a DTC
concerning Mass Air Flow (MAF) sensor:
– Check voltage supply of Mass Air Flow (MAF) sensor. → Anchor
If specified value is not obtained:
– Check signal and Ground (GND) wires of Mass Air Flow (MAF)
sensor. → Anchor
Voltage supply for Mass Air Flow (MAF) sensor, checking
Vehicles through 08.99
– Disconnect 4-pin connector -1- from Mass Air
Flow (MAF) Sensor -G70-- (-2-).
– Connect multimeter to terminals 1 +3 of
connector for voltage measurement.
– Start engine, and let run at idle.
Specified value: 11.0 to 15.0 V
– Switch ignition off.
If there is no voltage:
– Locate and repair open circuit using wiring
diagram: → Wiring diagrams, Troubleshooting
& Component locations
If voltage supply and wires are OK:
– Check signal and Ground (GND) wire of Mass
Air Flow (MAF) sensor. → Anchor
Vehicles from 09.99
– Disconnect 5-pin connector -1- from Mass Air
Flow (MAF) Sensor -G70- (-2-).
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Mass Air Flow Sensor, Checking
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– Connect multimeter to terminal 2 of connector
and engine Ground (GND) for voltage
measurement.
– Start engine, and let run at idle.
Specified value: 11.0 to 15.0 V
– Switch ignition off.
If there is no voltage:
– Check wire between 5-pin connector terminal 2
and the Fuel Pump (FP) Relay -J17- for open
circuit according to wiring diagram.
Wire resistance: max. 1.5 Ω
If voltage supply and wires are OK:
– Connect multimeter to terminal 4 of connector
and engine Ground (GND) for voltage
measurement.
– Switch ignition on.
Specified value: at least 4.5 V
– Switch ignition off.
If there is no voltage:
– Check signal and Ground (GND) wires of Mass
Air Flow (MAF) sensor.
Checking signal and Ground wires of Mass Air
Flow (MAF) Sensor
– Connect test box to control module wiring
harness → Chapter, connect test box for wiring
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Mass Air Flow Sensor, Checking
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test.
Vehicles through 08.99
– Check wires between test box and 4-pin
connector to Engine Control Module (ECM) for
open circuit according to wiring diagram.
Terminal 2 + socket 16
Terminal 4 + socket 17
Wire resistance: max. 1.5 Ω
Vehicles from 09.99
– Check wires between test box and 5-pin
connector to Engine Control Module (ECM) for
open circuit according to wiring diagram.
Terminal 3 + socket 12
Terminal 4 + socket 11
Terminal 5 + socket 13
Wire resistance: max. 1.5 Ω
Continue for all vehicles
– Check wires for short circuit to each other, to
vehicle Ground (GND) and to B+.
Specified value: ∞ Ω
If no DTCs are found in wires:
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Mass Air Flow Sensor, Checking
Page 5 of 5
– Replace Mass Air Flow (MAF) Sensor -G70→ Item.
– Erase DTC memory of Engine Control Module
(ECM) → Chapter, Diagnostic mode 4:
Reset/erase diagnostic data.
– Generate readiness code → Chapter.
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11/24/2010