Yamaha YZ450F Owner's Service Manual page 308

Fault code
Symptom
6 Defective intake air pressure
sensor.
7 Faulty ECU
TIP
If fault code Nos. 13 and 14 are both displayed, perform checkup and repair jobs for fault code No.
13 first.
Fault code
Symptom
Fail-safe system
Diagnostic code No.
Diagnostic tool display
Procedure
Or- Probable cause of malfunc-
der tion and check
1 The intake air pressure sen-
sor hose is damaged, discon-
nected, clogged, twisted or
bent.
13
Intake air pressure sensor: open or short circuit detected.
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
1000 m above sea level:
About 90 kPa
2000 m above sea level:
About 80 kPa
3000 m above sea level:
About 70 kPa
Replace the ECU.
14
Intake air pressure sensor: hose system malfunction (clogged
or detached hose)
Able to start engine
Able to drive vehicle
03
Displays the intake air pressure.
The atmospheric pressure is displayed on the Yamaha diagnostic
tool.
Maintenance job
Repair or replace the sensor
hose.
8-16
FUEL INJECTION SYSTEM
Turn "ON" the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
Reinstatement method
After starting the engine, idle
this and wait about 5 sec-
onds.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.