2011 YAMAHA YZ450F lock

7-20
FUEL INJECTION SYSTEM
Make sure that the engine is completely cool before checking the coolant temperature sensor.
Fault code No. 21
Symptom Coolant temperature sensor signal is not received properly.
Fail-safe system Able to start
Able to drive
Diagnostic code No. D06
FI diagnostic tool display -20–150°C
Cold engine: Displayed temperature is close to the ambient temperature.
Warm engine: Displayed temperature is the current coolant temperature.
Checking method Check the coolant temperature.
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the coolant temperature sensor coupler.
Disconnect the coupler and check the pins
(bent or broken terminals and locking condition
of the pins).Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.
2 Check the connection and locking condition of
the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 3.
3 Continuity of harness Open or short circuit → Replace.
Between coolant temperature sen-
sor coupler and ECU coupler
(Brown–Brown)
(Black/Blue–Black/Blue)Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 4.
4 Installed condition of sensor. Check that the sensor is installed
securely and that there are no
pinched leads.Check that the ECU
is installed securely and that there
are no pinched leads.
Incorrect installation → Reinstall
or repair.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 5.

7-21
FUEL INJECTION SYSTEM
Make sure that the engine is completely cool before checking the intake air temperature sensor.
5 Defective coolant temperature sensor. Execute the diagnostic mode (di-
agnostic code No. D06).
Cold engine: Displayed temper-
ature is close to the ambient
temperature.
Displayed value is incorrect → Re-
place. Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 6.
6 Malfunction in ECU. Replace the ECU.
Fault code No. 22
Symptom Intake air temperature sensor signal is not received properly.
Fail-safe system Able to start Able to drive
Diagnostic code No. D05
FI diagnostic tool display -20–100°C Cold engine: Displayed temperature is close to the ambient temperature.
Warm engine: Displayed temperature is approx imately 20°C higher than the ambient tem-
perature.
Checking method Check the temperature in the intake manifold. Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of the intake air temperature sensor coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins) Poor connection
→ Properly con-
nect, repair, or replace. Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.
Fault code No. 21
Symptom Coolant temperature sensor signal is not received properly.
Fail-safe system Able to start
Able to drive
Diagnostic code No. D06
FI diagnostic tool display -20–150°C Cold engine: Displayed temperature is close to the ambient temperature.
Warm engine: Displayed temperature is the current coolant temperature.
Checking method Check the coolant temperature. Item Item/components and probable cause Check or maintenance job Checking method

7-22
FUEL INJECTION SYSTEM
2 Check the connection and locking condition of the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins) Poor connection
→ Properly con-
nect, repair, or replace. Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item
3.
3 Continuity of harness Open or short circuit → Replace.
Between the intake air tempera-
ture sensor coupler and ECU cou-
pler.
(Brown/White–Brown/White)
(Black/Blue–Black/Blue) Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item
4.
4 Installed condition of sensor. Check that the sensor is installed securely and that there are no
pinched leads.Check that the ECU
is installed securely and that there
are no pinched leads.
Incorrect installation → Reinstall
or repair. Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item
5.
5 Defective intake temperature sensor. Execute the diagnostic mode (di- agnostic code No. D05).Cold engine: Displayed temper-
ature is close to the ambient
temperature.
Displayed value is incorrect → Re-
place. Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 6.
6 Malfunction in ECU. Replace the ECU. Fault code No. 22
Symptom Intake air temperature sensor signal is not received properly.
Fail-safe system Able to start Able to drive
Diagnostic code No. D05
FI diagnostic tool display -20–100°C Cold engine: Displayed temperature is close to the ambient temperature.
Warm engine: Displayed temperature is approx imately 20°C higher than the ambient tem-
perature.
Checking method Check the temperature in the intake manifold. Item Item/components and probable cause Check or maintenance job Checking method

7-23
FUEL INJECTION SYSTEM
Fault code No. 23
Symptom Atmospheric pressure sensor signal is not received properly.
Fail-safe system Able to start
Able to drive
Diagnostic code No. D02
FI diagnostic tool display Atmosphere
Checking method Measure the atmospheric pressure.
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the atmospheric pressure sensor coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.
2 Check the connection and locking condition of
the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 3.
3 Continuity of harness Open or short circuit → Replace.
Between atmospheric pressure
sensor coupler and ECU coupler.
(Black/Blue–Black/Blue)
(Pink–Pink)
(Blue–Blue)Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 4.
4 Installed condition of sensor. Check that the sensor is installed
securely and that there are no
pinched leads.Check that the ECU
is installed securely and that there
are no pinched leads.
Incorrect installation → Reinstall
or repair.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 5.

7-26
FUEL INJECTION SYSTEM
Fault code No. 33
Symptom Ignition system circuit signal is not received properly.
Fail-safe system Unable to start
Unable to drive
Diagnostic code No. D30
FI diagnostic tool display Actuates the ignition coil for five times every second.
The "WARNING" LED on the FI diagnostic tool comes on each time the ignition coil is ac-
tuated.
Checking methodCheck the spark five times.
• Connect an ignition checker.
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the ignition coil coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection→ Properly con-
nect, repair, or replace.Start the engine and let it
idle for approximately 5
seconds.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.
2 Check the connection and locking condition of
the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Start the engine and let it
idle for approximately 5
seconds.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 3.
3 Continuity of harness Open or short circuit → Replace.
Between Ignition coil coupler and
ECU coupler.
(Orange–Orange)Start the engine and let it
idle for approximately 5
seconds.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 4.

7-28
FUEL INJECTION SYSTEM
Fault code No. 39
Symptom Injection system circuit signal is not received properly.
Fail-safe system Unable to start
Unable to drive
Diagnostic code No. D36
FI diagnostic tool display Actuates the injector for five times every second.
The "WARNING" LED on the FI diagnostic tool comes on each time the fuel injector is ac-
tuated.
Checking method Check the operating sound of the injector five times.
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the fuel injector coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Start the engine and let it
idle for approximately 5
seconds.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item
2.
2 Faulty injector Defective → Replace.
Refer to "CHECKING THE FUEL
INJECTORS"Start the engine and let it
idle for approximately 5
seconds.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item
3.
3 Check the connection and locking condition of
the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Start the engine and let it
idle for approximately 5
seconds.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item
4.

7-31
FUEL INJECTION SYSTEM
Fault code No. 46
Symptom Power supply to the ECU is not normal.
Fail-safe system Able to start (depending on circumstances)
Able to drive vehicle (depending on circumstances)
Diagnostic code No. —
FI diagnostic tool display —
Checking method —
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Start the engine, set the
switch on the FI diagnostic
tool sub-wire harness to
"OFF" while the engine is
idling, and let the engine
continue to idle for 5 sec-
onds or more.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.
2 Continuity of harness Open or short circuit → Replace.
Between Rectifier/regulator and
the ECU
(Red–Red/White)
Between Rectifier/regulator and
the condenser.
(Red–Red)Start the engine, set the
switch on the FI diagnostic
tool sub-wire harness to
"OFF" while the engine is
idling, and let the engine
continue to idle for 5 sec-
onds or more.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 3.
3 Malfunction of the rectifier/regulator. Defective → Replace.
Refer to "CHECKING THE RECTI-
FIER/REGULATOR" section.Start the engine, set the
switch on the FI diagnostic
tool sub-wire harness to
"OFF" while the engine is
idling, and let the engine
continue to idle for 5 sec-
onds or more.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 4.

7-33
FUEL INJECTION SYSTEM
Fault code No. waiting for connection
Symptom Communication signal is not received.
Fail-safe system Able to start (unable when ECU is malfunctioning)
Able to drive vehicle (unable when ECU is malfunctioning)
Diagnostic code No. —
FI diagnostic tool display —
Checking method —
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the FI diagnostic tool coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.
2 Check the connection and locking condition of
the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 3.
3 Continuity of harness Open or short circuit → Replace.
Between FI diagnostic tool coupler
and ECU coupler.
(Light green–Light green)Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 4.
4 FI diagnostic tool malfunction Replace the FI diagnostic tool. Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 5.
5 Malfunction in ECU. Replace the ECU.