Yamaha YZ450F(B) 2012 Owner's Service Manual page 216

Fault code No.
Symptom
Fail-safe system
Diagnostic code No.
FI diagnostic tool display
Checking method
Item Item/components and probable cause
4 Defective AC magneto.
5 Malfunction in ECU.
Fault code No.
Symptom
Fail-safe system
Diagnostic code No.
FI diagnostic tool display
Checking method
Item Item/components and probable cause
1 Malfunction in ECU.
46
Power supply to the ECU is not normal.
Able to start (depending on circumstances)
Able to drive vehicle (depending on circumstances)
—
—
—
50
ECU internal malfunction
Unable to start
Unable to drive
—
—
—
FUEL INJECTION SYSTEM
Check or maintenance job
Defective → Replace.
Refer to "CHECKING THE AC
MAGNETO" section.
Replace the ECU.
Check or maintenance job
Replace the ECU.
7-32
Checking method
Start the engine, set the
switch on the FI diagnostic
tool sub-wire harness to
"OFF" while the engine is
idling, and let the engine
continue to idle for 5 sec-
onds or more.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 5.
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 fin-
ished.