AUDI A4 1997 B5 / 1.G AFC Engine Mass Air Flow Sensors Checking Workshop Manual
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Mass Air Flow (MAF) sensor,
checking
Notes:
To functionally check the Mass Air Flow (MAF)
sensor Repair Group 01, Basic setting,
display group 001, display field 2.
Component locations page 24
-1 .
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
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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( )
- Check wiring for continuity between terminal 2
and intake manifold Ground (GND).
Specified value: max. 0.5
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Checking signal wire
If the specified value is not obtained: - Connect VAG 1598/19 test box to ECM harness connector page 01
-
255
.
- Check signal wire for continuity between MAF sensor connector
terminal 1 and test box socket A12.
Specified value: max.1.0
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. - Find short circuit or open circuit; repair as necessary.MAF sensor connector terminal
ECM connector A terminal
1 A12
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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
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Page 5 of 5
max. depending on engine speed (RPM)
If the specified value is not obtained:
- Replace Mass Air Flow (MAF) sensor.
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