Yamaha MBK MW125 2014 Service Manual page 335

Fault code No.
Item
3 Wire harness continuity.
4 Installed condition of coolant
temperature sensor.
Check for looseness or pinch-
ing.
5 Defective coolant temperature
sensor.
6 Malfunction in ECU.
TIP
If fault code numbers "21" and "37" are both indicated, take the actions specified for fault code number
"21" first.
Fault code No. 22
Fault code No.
Item
Fail-safe system
Diagnostic code No.
Tool display
Procedure
Probable cause of malfunc-
Item
tion and check
21
Coolant temperature sensor: open or short circuit detected.
Open or short circuit → Replace
the wire harness.
Between coolant temperature
sensor coupler and ECU cou-
pler.
green/red–green/red
black/blue–black/blue
Improperly installed sensor →
Reinstall or replace the sensor.
Execute the diagnostic mode.
(Code No. 06)
When engine is cold:
Displayed temperature is close
to the ambient temperature.
The displayed temperature is
not close to the ambient tem-
perature → Check the coolant
temperature sensor.
Replace thermostat assembly, if
defective.
Refer to "CHECKING THE
COOLANT TEMPERATURE
SENSOR" on page 8-67.
Replace the ECU.
Refer to "REPLACING THE
ECU (engine control unit)" on
page 8-59.
22
Intake air temperature sensor: open or short circuit detected.
Able to start engine
Able to drive vehicle
05
Displays the intake air temperature.
Compare the actually measured intake air temperature with the meter
display value.
Maintenance job
8-38
FUEL INJECTION SYSTEM
Turn the main switch to "ON".
Fault code number is not dis-
played → Service is finished.
Fault code number is displayed
→ Go to item 4.
Turn the main switch to "ON".
Fault code number is not dis-
played → Service is finished.
Fault code number is displayed
→ Go to item 5.
Turn the main switch to "ON".
Fault code number is not dis-
played → Service is finished.
Fault code number is displayed
→ Go to item 6.
Confirmation of service com-
pletion