Yamaha YZ450F Owner's Service Manual page 207

Fault code No.
Symptom
Fail-safe system
Diagnostic code No.
FI diagnostic tool display
Checking method
Item Item/components and probable cause
5 Defective coolant temperature sensor.
6 Malfunction in ECU.
Make sure that the engine is completely cool before checking the intake air temperature sensor.
Fault code No.
Symptom
Fail-safe system
Diagnostic code No.
FI diagnostic tool display
Checking method
Item Item/components and probable cause
1 Check the connection and locking condition of
the intake air temperature sensor coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)
21
Coolant temperature sensor signal is not received properly.
Able to start
Able to drive
D06
-20–150°C
Cold engine: Displayed temperature is close to the ambient temperature.
Warm engine: Displayed temperature is the current coolant temperature.
Check the coolant temperature.
22
Coolant temperature sensor signal is not received properly.
Able to start
Able to drive
D05
-20–100°C
Cold engine: Displayed temperature is close to the ambient temperature.
Warm engine: Displayed temperature is approximately 20°C higher than the ambient tem-
perature.
Check the temperature in the intake manifold.
FUEL INJECTION SYSTEM
Check or maintenance job
Execute the diagnostic mode (di-
agnostic code No. D06).
Cold engine: Displayed temper-
ature is close to the ambient
temperature.
Displayed value is incorrect → Re-
place.
Replace the ECU.
Check or maintenance job
Poor connection → Properly con-
nect, repair, or replace.
7-21
Checking method
Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 6.
Checking method
Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.