Yanmar 4BY, Service Manual, Page: 271 / 275

TROUBLESHOOTING
13-10
BY Service Manual
Trouble Codes
TROUBLE CODES
Working Procedure
Try to form a comprehensive view of the problem. Start by asking the operator the following:
• Symptoms
• Conditions in which the fault occurs
• How often the fault occurs
• If the trouble codes have been erased
Then, extract all the stored trouble codes.
Compare them and try to conclude the probable cause of the fault before taking any other measures. The
trouble codes are stored in the order they were registered.
Diagnostic Trouble Codes
Some conditions will produce an alarm but do not generate a trouble code. An example is engine overheat
(over 108°C) caused by an obstructed seawater inlet. The overheat alarm will sound and the engine torque
will be reduced to proect the engine, but no code will be set.
Conditions that set a trouble code are generally caused by a sensor or other component sending and out of
normal range signal to the ECU. An example is a disconnected intake air pressure sensor which would set
a P0237 code.
Code Fail Mode
Run or
Condition
Engine
Can
Start
Check
Engine
Alarm
No
Code
Coolant Temp Under 0°C (32°F) 1000 rpm yes no
No
Code
Coolant Temp Over 108°C (226°F) reduce yes alarm
No
Code
Charge Air Temp Over 110°C (230°F) reduce yes no
No
Code
Boost Pressure
Reading
4BY - over 1.9 bar (27.5 psi) (relative*) or 2.9 bar
(42.0 psi) (absolute**)
6BY - over 2.3 bar (33.3 psi) (relative*) or 3.3 bar
(42.9 psi) (absolute**)
reduce yes alarm
No
Code
Fuel Temperature Over 90°C (194°F) reduce yes no
No
Code
Neutral Switch
Only in case of analog throttle or in case of CAN-fault
(U0001), wrong configuration - neutral position
no no alarm
P0001 Fuel Metering Unit Not connected reduce yes alarm
P0003 Fuel Metering Unit Short circuit to Ground no no alarm
P0004 Fuel Metering Unit Short circuit to B+ reduce yes alarm
P0087
Fuel Rail Pressure
System Deviation
Fuel rail pressure out of range
reduce or
shut off
depends
on fault
alarm