HYOSUNG AQUILA 250 FI, Service Manual, Page: 34 / 90

33
FI SYSTEM DIAGNOSIS 4-1-24
▣ ▣
INSPECTION
◈
Step 1
1) Remove the fuel tank.
2) Turn the ignition switch “OFF” position.
3) Check the IAT sensor coupler for loose or poor
contacts.
If OK, then measure the IAT sensor voltage at the
wire side coupler.
4) Disconnect the coupler and turn the ignition switch
“ON” position.
“C21” IAT SENSOR CIRCUIT MALFUNCTION
DETECTED CONDITION POSSIBLE CAUSE
● IAT sensor circuit open or short.
●
IAT sensor malfunction.
● ECU malfunction.
YES
NO
IAT sensor voltage
4.5 ~ 5.5 V
( � Lg - � Ground )
( � Lg - � BW )
Is the voltage OK?
Tester knob indication : Voltage ( )
C21
CODE
CODE
①
[ 2 1 2 1 1 2 2 1 ]
Output voltage is out of the specified range.
0.1 V
�
Sensor voltage < 4.6 V
5) Measure the voltage between Lg wire terminal and
ground.
6) If OK, then measure the voltage between Lg wire
terminal and BW wire terminal.
Go to Step 2.
●
Loose or poor contacts on the
ECU coupler.
● Open or short circuit in the Lg
wire or BW wire.