GDI ± Troubleshooting
13A-16
Code No.12 Air flow sensor system Probable cause
Range of check
D Engine speed is 500 r/min or more.
Set conditions
D Sensor output frequency is 3.3 Hz or less for 4 seconds.
D Malfunction of the air flow sensor
D Open circuit or short-circuited harness wire of air
flow sensor circuit
D Malfunction of the engine-ECU
NG
Repair
NG
Repair
OK
Replace the engine-ECU.
NG
Repair
NG
Replace the air flow sensor.
NG
Repair
NG
Replace the air flow sensor.
NG
Repair
OK
Replace the engine-ECU.
NG
OK
Check trouble symptom.
OK
Check the following connector:
C-19
OK
Check trouble symptom.
(2) NG
Measure at the engine-ECU connector
C-19.
D Connect the connector
D Voltage between 76 and earth
(Ignition switch: ON)
OK: 6 ± 9 V
NG
Check the following connector:
A-71
OK
Check trouble symptom.
OK
Check the following connector:
A-71
NG
Check the harness wire between the
engine-ECU and the air flow sensor,
and repair if necessary.
OK
Check trouble symptom.
(2), (3) NG
Check the following connectors:
A-36, C-18, C-19
Measure at the air flow sensor connec-
tor A-71.
D Connect the connector
(Use the test harness MB991709)
(1) Voltage between 3 and earth
(Engine: Idling)
OK: 2.2 ± 3.2 V
(2) Voltage between 7 and earth
OK: 0 ± 0.1 V
(Engine: Idling)
OK: 6 ± 9 V
(Engine speed: 4,000
r/min)
(1) NG
Measure at the air flow sensor connec-
tor A-71.
D Disconnect the connector, and
measure at the harness side.
(1) Voltage between 4 and earth
(Ignition switch: ON)
OK: System voltage
(2) Voltage between 3 and earth
(Ignition switch: ON)
OK: 4.8 ± 5.2 V
(3) Continuity between 5 and earth
OK: Continuity
(1) NG
Check the harness wire between the
air flow sensor and the engine control
relay, and repair if necessary.
NG
Repair
OK
Check trouble symptom.
Check the following connector:
A-36
NG
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