Yamaha YZ450F Owner's Service Manual page 314

Fault code
Symptom
5 Defective intake air tempera-
ture sensor.
6 Faulty ECU
Fault code
Symptom
Fail-safe system
Diagnostic code No.
Diagnostic tool display
Procedure
Or- Probable cause of malfunc-
der tion and check
1 The vehicle has overturned.
2 Mounted condition of ECU.
Check for looseness or
pinching.
Check the mounted condition
for correctness.
3 Faulty ECU
22
Intake air temperature sensor: open or short circuit detected.
Execute the diagnostic mode.
(Code No. 05)
When the machine is cold,
displayed temperature is
close to the ambient temper-
ature.
Improper display  Replace
the intake air temperature
sensor.
Replace the ECU.
30
The vehicle has overturned.
Able to start engine
Unable to drive vehicle
08
Displays the lean angle sensor output voltage.
• 1.0 V (upright)
• 4.0 V (overturned)
Remove the ECU, and incline it 45 ° or more.
Maintenance job
Raise the vehicle upright.
Improperly mounted ECU 
Remount the ECU.
Execute the diagnostic mode.
(Code No. 08)
When the vehicle is upright:
1.0 V
When the vehicle is over-
turned: 4.0 V
Improper display  Replace
the ECU.
8-22
FUEL INJECTION SYSTEM
Turn "ON" the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
Reinstatement method
Turn "ON" the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
Turn "ON" the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.