Dtc P0427 Or P0428 (Flash Code 48) - Isuzu N 2008 Series Workshop Manual

1A-166 Engine Control System (4JJ1)

DTC P0427 or P0428 (Flash Code 48)

Circuit Description
The exhaust temperature sensor 1 is installed to the
diesel particulate defuser (DPD) housing. The exhaust
temperature sensor 1 is a variable resistor and it
measures the temperature of the exhaust gas in front of
DPD filter. The sensor has a signal circuit and a low
reference circuit. The ECM supplies 5 volts to the
signal circuit and a ground for the low reference circuit.
When the exhaust temperature sensor 1 is cold, the
sensor resistance is
temperature increases,
decreases. With high sensor resistance, the ECM
detects a high voltage on the signal circuit. With lower
sensor resistance, the ECM detects a lower voltage on
the signal circuit. If the ECM detects an excessively low
or high signal voltage, DTC P0427 or P0428 will set.
Condition for Running the DTC
• DTCs P060B and P0697 are not set. (DTC P0427)
• DTCs P0112, P0113, P0116, P0117, P0118,
P060B, P0651, P0697, P2227, P2228 and P2229
are not set. (DTC P0428)
• The battery voltage is between 18 to 32 volts.
• The ignition switch is ON.
• The engine coolant temperature is more than
(80°C) (176 °F). (DTC P0428)
• The engine speed is more than 1600 RPM. (DTC
P0428)
• The fuel injection quantity is more than a
predetermined value. (DTC P0428)
• The vehicle is running or the PTO control is
inactive.
Circuit/ System Testing DTC P0427
Step
Did you perform the Diagnostic System Check -
1 Engine Controls?
1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
2
4. Monitor the DTC Information with a scan tool.
Is DTC P0697 also set?
Observe the Exhaust Temperature Sensor 1
parameter with a scan tool.
3
Is the Exhaust Temperature Sensor 1 parameter
less than the specified value?
high. When the exhaust
the sensor resistance
Action
• The engine run time is longer than 3 to 10 minutes.
(DTC P0428)
Condition for Setting the DTC
• The ECM detects that the exhaust temperature
sensor 1 signal voltage is less than 0.2 volts for 3
seconds. (DTC P0427)
• The ECM detects that the exhaust temperature
sensor 1 signal voltage is more than 4.85 volts for
5 seconds. (DTC P0428)
Action Taken When the DTC Sets
• The ECM illuminates 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
Condition for Clearing the DTC
• Refer to DTC Type Definitions for Condition for
Clearing the MIL/ DTC - Type A.
Diagnostic Aids
• If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.
• Use the Temperature vs. Resistance table to test
the exhaust temperature sensor 1 at various
temperature levels to evaluate the possibility of a
skewed sensor.
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Value(s) Yes
—
Go to Step 2
—
Go to DTC P0697
0.2 volts
Go to Step 4
No
Go to Diagnostic
System Check -
Engine Controls
Go to Step 3
Go to Diagnostic
Aids