Yamaha YZ450FN 2022, Owner'S Service Manual, Page: 317 / 366

FUEL INJECTION SYSTEM
8-36
Fault code No. 50
TIP
Before troubleshooting, disconnect the starter motor lead from the starter relay.
Fault code No. 70
TIP
It is not a malfunction.
If the engine is forcibly stopped by leaving idle, the recovered state is recorded by malfunction mode.
6 Delete the fault code. Confirm that the fault code has
a condition of “Recovered”
using the Yamaha diagnostic
tool, and then delete the fault
code.
Fault code No. 50
Item ECU: faulty ECU memory.
Fail-safe system
Unable to start engine
Unable to drive vehicle
Diagnostic code No.
—
Diagnostic tool display
—
Procedure
—
Item
Probable cause of malfunc-
tion and check
Maintenance job
Confirmation of service com-
pletion
1 Faulty ECU. Replace the ECU. 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.
Check that the fault code num-
ber is not displayed.
Fault code No. 70
Item
Engine forcibly stops when the vehicle is left idling for a long period
of time.
Fail-safe system
—
Unable to drive vehicle
Diagnostic code No.
—
Diagnostic tool display
—
Procedure
—
Item
Probable cause of malfunc-
tion and check
Maintenance job
Confirmation of service com-
pletion
Fault code No. 46
Item
Vehicle system power supply: normal voltage is not supplied to the
ECU.