Yamaha WR450F Owner's Service Manual page 373

Fault code No.
Item
5 Defective coolant tempera-
ture sensor.
6 Malfunction in ECU.
TIP
• Make sure that the engine is completely cool before checking the intake air temperature sensor.
• Before troubleshooting, disconnect the starter motor lead from the starter relay.
Fault code No.
Item
Fail-safe system
Diagnostic code No.
Diagnostic tool display
Procedure
Probable cause of malfunc-
Item
tion and check
1 Connection of intake air tem-
perature sensor coupler.
Check the locking condition
of the coupler.
Disconnect the coupler and
check the pins (bent or bro-
ken terminals and locking
condition of the pins).
2 Connection of wire harness
ECU coupler.
Check the locking condition
of the coupler.
Disconnect the coupler and
check the pins (bent or bro-
ken terminals and locking
condition of the pins).
21
Coolant temperature sensor: open or short circuit detected.
Execute the diagnostic mode.
(Code No. 06)
When engine is cold:
Displayed temperature is
close to the ambient temper-
ature.
The displayed temperature is
not close to the ambient tem-
perature.  Check the cool-
ant temperature sensor.
Replace if defective.
Refer to "CHECKING THE
COOLANT TEMPERATURE
SENSOR" on page 9-78.
Replace the ECU.
22
Intake air temperature sensor: open or short circuit detected.
Able to start engine
Able to drive vehicle
05
Displays the intake air temperature.
Compare the actually measured intake air temperature with the
Yamaha diagnostic tool display value.
Maintenance job
Improperly connected 
Connect the coupler securely
or repair/replace the wire har-
ness.
Improperly connected 
Connect the coupler securely
or repair/replace the wire har-
ness.
9-43
FUEL INJECTION SYSTEM
Push the start switch.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 6.
Confirmation of service
completion
Push the start switch.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 2.
Push the start switch.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 3.