Yamaha YZ 2018 Series, Owner'S Service Manual

Page: 330 / 402

FUEL INJECTION SYSTEM
8-31
TIP
• If fault code numbers 13 and 14 are both displayed, perform the checks and maintenance jobs for
fault code number 13 first.
• Before troubleshooting, disconnect the starter motor lead from the starter relay.
4 Installed condition of intake
air pressure sensor.
Check for looseness or
pinching. Improperly installed sensor

Reinstall or replace the
sensor.
Push the start switch.
Fault code number is not dis-
played

Service is finished.
Fault code number is dis-
played

Go to item 5.
5 Defective intake air pressure
sensor. Execute the diagnostic mode.
(Code No. 03)
When engine is stopped:
Atmospheric pressure at the
current altitude and weather
conditions is indicated.
At sea level: Approx. 101 kPa
1000 m above sea level: Ap-
prox. 90 kPa
2000 m above sea level: Ap-
prox. 80 kPa
3000 m above sea level: Ap-
prox. 70 kPa
When engine is cranking:
Make sure that the indication
value changes.
The value does not change
when engine is cranking.

Check the intake air pressure
sensor.
Replace if defective.
Refer to “CHECKING THE
INTAKE AIR PRESSURE
SENSOR” on page 8-71.
Push the start switch.
Fault code number is not dis-
played

Service is finished.
Fault code number is dis-
played

Go to item 6.
6 Malfunction in ECU. Replace the ECU.
Fault code No. 14
Item
Intake air pressure sensor: hose system malfunction (clogged
or detached hose).
Fail-safe system Able to start engine
Able to drive vehicle
Diagnostic code No. 03
Diagnostic tool display Displays the intake air pressure.
Procedure Operate the throttle while pushing the start switch.(If the display
value changes, the performance is OK.)
Item
Probable cause of malfunc-
tion and check
Maintenance job
Confirmation of service
completion
Fault code No. 13
Item Intake air pressure sensor: open or short circuit detected.