Dtc P0088 (Flash Code 118) - Isuzu 2008MY N Series Workshop Manual

DTC P0088 (Flash Code 118)

Description
The common rail fuel system is comprised of two fuel
pressure sections: a suction side between the fuel tank
and the fuel supply pump and a high-pressure side
between the fuel supply pump and the fuel injectors.
Fuel is drawn from the fuel tank via a feed pump and
then pumped into the fuel rail by two plungers, all of
which are internal to the fuel supply pump. This high
pressure is regulated by the ECM using the fuel rail
pressure (FRP) regulator dependant upon values from
the FRP sensor attached to the fuel rail.
If the ECM detects that the fuel pressure went
excessively high for a certain length of time, this DTC
will set (First Stage). If the ECM detects that during the
same ignition cycle the fuel pressure rose even higher
than the amount to set DTC P0088 for a certain length
of time, the MIL will be illuminated (Second Stage). If
the MIL is illuminated, the fuel pressure was too high
and the pressure limiter valve did not active or did not
active quick enough.
Condition for Running the DTC
• DTCs P0192, P0193, P060B and P0651 are not
set.
• The ignition switch is ON.
• The engine is running.
Condition for Setting the DTC
First Stage
• The ECM detects that the fuel rail pressure is more
than 185 MPa (26,800 psi) for longer than 5
seconds.
Second Stage
• The ECM detects that the fuel rail pressure is more
than 190 MPa (27,500 psi) for longer than 5
seconds.
Action Taken When the DTC Sets
First Stage
• The ECM will not illuminate the MIL or SVS lamp.
Refer to DTC Type Definitions for Action Taken
When the DTC Sets - Type D. (Euro 4
specification)
• The ECM illuminates the MIL when the diagnostic
runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
(Except Euro 4 specification)
• The ECM limits fuel injection quantity.
Circuit/ System Testing DTC P0088
Step
Did you perform the Diagnostic System Check
1
- Engine Controls?
Action
Engine Control System (4HK1)
• The ECM inhibits pilot injection.
Second Stage
• The ECM illuminates the MIL when the diagnostic
runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
• The ECM limits fuel injection quantity.
• The ECM inhibits pilot injection.
• The ECM inhibits EGR control.
Condition for Clearing the DTC
First Stage
• Refer to DTC Type Definitions for Condition for
Clearing the DTC - Type D. (Euro 4 specification)
• Refer to DTC Type Definitions for Condition for
Clearing the MIL/ DTC - Type A. (Except Euro 4
specification)
Second Stage
• Refer to DTC Type Definitions for Condition for
Clearing the MIL/ DTC - Type A.
Diagnostic Aids
• An intermittently sticking FRP regulator may have
allowed the fuel pressure to become high enough
to set this DTC.
• Normal Fuel Rail Pressure readings on the scan
tool with the engine running in neutral at idle is
around 27 to 33 MPa (3,900 to 4,800 psi) after
warm up.
• A skewed FRP sensor value can set this DTC. The
FRP Sensor on the scan tool should read 0.9 to
1.0 volt with the ignition switch ON and engine
OFF after the engine has stopped running for a
minimum of 1 minute.
Test Description
The numbers below refers to the step number on the
Circuit/ System Testing.
7. This step checks for a fuel restriction by determining
if a high vacuum is being pulled on the fuel system
during normal operation.
8. This step checks for an air leak on the suction side of
the fuel system by determining if a vacuum can be
pulled when a fuel line is plugged.
Schematic Reference: Fuel System Routing Diagram
and Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Value(s) Yes
—
Go to Step 2
1A-79
No
Go to Diagnostic
System Check -
Engine Controls