Dtc P0117 Or P0118 (Flash Code 23) - Isuzu N 2008 Series Workshop Manual

1A-106 Engine Control System (4JJ1)

DTC P0117 or P0118 (Flash Code 23)

Circuit Description
The engine coolant temperature (ECT) sensor is
installed to the thermostat housing. The ECT sensor is
a variable resistor and it measures the temperature of
the engine coolant. 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 ECT sensor is cold, the sensor resistance is
high. When the engine coolant temperature increases,
the sensor resistance 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
P0117 or P0118 will set.
Condition for Running the DTC
• DTCs P060B and P0697 are not set.
• The battery voltage is between 18 to 32 volts.
• The ignition switch is ON.
• The engine run time is longer than 5 seconds.
(DTC P0118)
Condition for Setting the DTC
• The ECM detects that the ECT sensor signal
voltage is less than 0.1 volts for 3 seconds. (DTC
P0117)
Circuit/ System Testing DTC P0117
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 Engine Coolant Temperature (ECT)
Sensor parameter with a scan tool.
3
Is the ECT Sensor parameter less than the
specified value?
1. Turn OFF the ignition.
2. Disconnect
connector.
4
3. Turn ON the ignition, with the engine OFF.
Is the ECT Sensor parameter more than the
specified value?
Action
the ECT sensor harness
• The ECM detects that the ECT sensor signal
voltage is more than 4.85 volts for 3 seconds.
(DTC P0118)
Action Taken When the DTC Sets
• 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 uses an ECT substitution of default
value.
• The ECM inhibits EGR control.
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 ECT sensor at various temperature levels to
evaluate the possibility of a skewed sensor. A
skewed sensor could result in poor driveability
concerns.
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
0.1 volts
Go to Step 4
4.5 volts
Go to Step 6
No
Go to Diagnostic
System Check -
Engine Controls
Go to Step 3
Go to Diagnostic
Aids
Go to Step 5