Yanmar 4BY - Engine Faults and Torque Limitations; Torque Limitation for Failed Sensors; Torque Limitation for Smoke Limitation; Introduction

TROUBLESHOOTING
BY Service Manual
13-3
Introduction
INTRODUCTION
This section of the Service Manual contains information and diagnostic troubleshooting charts to accurately
diagnose engine, starter, or alternator problems.
ENGINE FAULTS AND TORQUE
LIMITATIONS
Torque Limitation for Failed Sensors
This limitation occurs only if a fault is active. It will
be displayed on the display-alarm and a P-Code
will be saved in the system. The alarm consists fo
an audible alarm, a warning light, and a check
engine light on the digital display. The codes can be
read with a diagnostic tester. A substitute torque
map is activated and torque reduction occurs. This
fault occurs if there is an electrical problem in the
respective sensor or actuator.
The following failures activate this mode:
• Coolant temperature sensor
• Camshaft sensor
• Boost pressure sensor
• Rail pressure system
• Throttle signal missing
• Sensor supply voltage
• Metering unit failure
• Fuel injector failure
• Rail pressure governor deviation
Torque Limitation for Smoke
Limitation
In the case of this limitation, there are two possible
situations:
If an electronic fault occurs, it will be displayed on
the display-alarm and a P-Code is saved in the
system. These codes can be read with a diagnostic
tester. A substitute map is activated and torque
reduction occurs as in Torque Limitation for Failed
Sensors on this page.
However, if the boost pressure is too low or the
intake air temperature is too high, this limitation is
activated for the prevention of black smoke and
torque reduction also occurs. In this case there is
not an alarm on the display and no P-Code
appears.
The following failures activate this mode:
• Intake air temperature too high
• Boost pressure too low
• Air intake system damage (e.g. hole in intake air
pipe)