Yamaha YZ450FX 2019 Owner's Service Manual page 332

Fault code No.
Item
5 Defective intake air tempera-
ture sensor.
6 Faulty ECU.
7 Delete the fault code.
Fault code No. 30
Fault code No.
Item
Fail-safe system
Diagnostic code No.
Diagnostic tool display
Procedure
Probable cause of malfunc-
Item
tion and check
1 The vehicle has overturned.
2 Mounted condition of ECU.
Check for looseness or pinch-
ing.
Check the mounted condition
for correctness.
22
Intake air temperature sensor: open or short circuit detected.
Execute the diagnostic mode.
(Code No. 05)
When the machine is cold, dis-
played temperature is close to
the ambient temperature.
Improper display  Replace the
intake air temperature sensor.
Replace the ECU.
Confirm that the fault code has
a condition of "Recovered"
using the Yamaha diagnostic
tool, and then delete the fault
code.
30
The vehicle has overturned.
Able to start engine
Unable to drive vehicle
08
Displays the lean angle sensor output voltage.
• 0.4–1.4 (V) (upright)
• 3.7–4.4 (V) (overturned)
Remove the ECU, and incline it 45 or more.
Maintenance job
Raise the vehicle upright.
Improperly mounted ECU 
Remount the ECU.
8-37
FUEL INJECTION SYSTEM
Start switch to ON (main relay
ON), and then check the condi-
tion of the fault code using the
malfunction mode of the
Yamaha diagnostic tool.
Condition is "Recovered"  Go
to item 7 and finish the service.
Condition is "Detected"  Go to
item 6.
Service is finished.
Confirmation of service com-
pletion
Start switch to ON (main relay
ON), wait 10 seconds, then
check the condition of the fault
code using the malfunction
mode of the Yamaha diagnostic
tool.
Condition is "Recovered"  Go
to item 4 and finish the service.
Condition is "Detected"  Go to
item 2.
Start switch to ON (main relay
ON), wait 10 seconds, then
check the condition of the fault
code using the malfunction
mode of the Yamaha diagnostic
tool.
Condition is "Recovered"  Go
to item 4 and finish the service.
Condition is "Detected"  Go to
item 3.