Yamaha YZ250FX 2021, Owner'S Service Manual

Page: 312 / 378

FUEL INJECTION SYSTEM
8-25
1 Connection of intake air pres-
sure sensor 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).
Improperly connected

Con-
nect the coupler securely, or
repair/replace the wire harness.
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 2.
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).
Improperly connected

Con-
nect the coupler securely, or
repair/replace the wire harness.
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.
3 Wire harness continuity. Open or short circuit

Replace
the wire harness.
Between intake air pressure
sensor coupler and ECU cou-
pler.
pink/black–pink/black
blue–blue
black/blue–black/blue
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.
4 Mounted condition of intake air
pressure sensor.
Check for looseness or pinch-
ing.
Check the mounted position for
correctness.
Improperly mounted sensor

Remount or replace the sensor.
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.
5 Defective intake air pressure
sensor.
Execute the diagnostic mode.
(Code No. 03)
Atmospheric pressure at the
current altitude and weather
conditions is indicated.
0 m above sea level: About 101
kPa (about 3.63 V)
1000 m above sea level: About
90 kPa (about 3.30 V)
2000 m above sea level: About
80 kPa (about 3.00 V)
3000 m above sea level: About
70 kPa (about 2.70 V)
Abnormal display

Intake air
pressure sensor is defective

Replace the intake air pressure
sensor.
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.
6 Faulty ECU. Replace the ECU. Service is finished.
7 Delete the fault code. Confirm that the fault code has
a condition of “Recovered”
using the Yamaha diagnostic
tool, and then delete the fault
code.
Fault code No. 13
Item Intake air pressure sensor: open or short circuit detected.