Yamaha YZ450FN 2022 Owner's Service Manual page 313

Fault code No.
Item
6 Delete the fault code.
Fault code No. 41
Fault code No.
Item
Fail-safe system
Diagnostic code No.
Diagnostic tool display
Procedure
Probable cause of malfunc-
Item
tion and check
1 Faulty ECU.
Fault code No. 43
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 main relay cou-
pler.
Check the locking condition of
the coupler.
Disconnect the coupler, and
check the pins (bent or broken
terminals and locking condition
of the pins).
39
Injector: open or short circuit detected.
Confirm that the fault code has
a condition of "Recovered"
using the Yamaha diagnostic
tool, and then delete the fault
code.
41
ECU: built-in lean angle sensor malfunction.
Unable to start engine
Able 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
Replace the ECU.
43
Fuel system voltage: incorrect voltage supplied to the main relay
and CCU.
Able to start engine
Able to drive vehicle
09
Fuel system voltage
Approximately 12.0 (V)
Disconnect the main relay, and push the start switch.
Maintenance job
Improperly connected  Con-
nect the coupler securely, or
repair/replace the wire harness.
8-32
FUEL INJECTION SYSTEM
Confirmation of service com-
pletion
Service is finished.
Confirmation of service com-
pletion
Press the start switch and the
engine stop switch alternately to
switch the power supply (= main
relay) from "ON  OFF  ON".
Check the condition of the fault
code using the malfunction
mode of the Yamaha diagnostic
tool.
Condition is "Recovered"  Go
to item 6 and finish the service.
Condition is "Detected"  Go to
item 2.