Yamaha YZ450FN 2022 Owner's Service Manual page 307

Fault code No.
Item
2 Connection of wire harness
ECU coupler.
Check the locking condition of
the coupler.
Disconnect the coupler, and
check the pins (for bent or bro-
ken terminals and locking condi-
tion of the pins).
3 Wire harness continuity.
4 Mounted condition of coolant
temperature sensor.
Check for looseness or pinch-
ing.
Check the mounted position for
correctness.
5 Defective coolant temperature
sensor.
6 Faulty ECU.
7 Delete the fault code.
21
Coolant temperature sensor: open or short circuit detected.
Improperly connected  Con-
nect the coupler securely, or
repair/replace the wire harness.
Open or short circuit  Replace
the wire harness.
Between coolant temperature
sensor coupler and ECU cou-
pler.
green/white–green/white
black/blue–black/blue
Improperly mounted sensor 
Remount or replace the sensor.
Execute the diagnostic mode.
(Code No. 06)
When the machine is cold, dis-
played temperature is close to
the ambient temperature.
Improper display  Replace the
coolant temperature sensor.
Refer to "RADIATOR" on page
6-2.
Replace the ECU.
Confirm that the fault code has
a condition of "Recovered"
using the Yamaha diagnostic
tool, and then delete the fault
code.
8-26
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 3.
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 4.
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 5.
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.