Yamaha YZ 2023 Series Owner's Service Manual page 321

Fault code No.
Item
3 Connection of sub wire harness
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).
4 Wire harness continuity.
5 Mounted condition of ignition
coil.
Check for looseness or pinch-
ing.
Check the mounted condition
for correctness.
6 Defective ignition coil. (test the
primary coils for continuity)
7 Faulty ECU.
8 Delete the fault code.
33
Ignition coil: open or short circuit detected in the primary lead of
the ignition coil.
Improperly connected  Con-
nect the coupler securely, or
repair/replace the sub wire har-
ness.
Open or short circuit  Replace
the wire harness.
Between ignition coil coupler
and ECU coupler.
orange–orange
red–red/blue
Improperly mounted sensor 
Remount or replace the ignition
coil.
Check the primary resistance of
the ignition coil.
Refer to "CHECKING THE
IGNITION COIL" on page 8-54.
Execute the diagnostic mode.
(Code No. 30)
No spark  Replace the ECU.
Confirm that the fault code has
a condition of "Recovered"
using the Yamaha diagnostic
tool, and then delete the fault
code.
8-34
FUEL INJECTION SYSTEM
Start the engine and let it idle for
approximately 5 seconds.
Check the condition of the fault
code using the malfunction
mode of the Yamaha diagnostic
tool.
Condition is "Recovered"  Go
to item 8 and finish the service.
Condition is "Detected"  Go to
item 4.
Start the engine and let it idle for
approximately 5 seconds.
Check the condition of the fault
code using the malfunction
mode of the Yamaha diagnostic
tool.
Condition is "Recovered"  Go
to item 8 and finish the service.
Condition is "Detected"  Go to
item 5.
Start the engine and let it idle for
approximately 5 seconds.
Check the condition of the fault
code using the malfunction
mode of the Yamaha diagnostic
tool.
Condition is "Recovered"  Go
to item 8 and finish the service.
Condition is "Detected"  Go to
item 6.
Start the engine and let it idle for
approximately 5 seconds.
Check the condition of the fault
code using the malfunction
mode of the Yamaha diagnostic
tool.
Condition is "Recovered"  Go
to item 8 and finish the service.
Condition is "Detected"  Go to
item 7.
Service is finished.