Dtc P0112 Or P0113 (Flash Code 22) - Isuzu N 2008 Series Workshop Manual

1A-100 Engine Control System (4JJ1)

DTC P0112 or P0113 (Flash Code 22)

Circuit Description
The intake air temperature (IAT) sensor is fitted
between the air cleaner and turbocharger. It is internal
to the mass air flow (MAF) sensor (Euro 4
specification). The IAT sensor is a variable resistor and
it measures the temperature of the air entering the
engine. 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 IAT sensor is cold, the sensor resistance is
high. When the air 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 P0112 or
P0113 will set.
Condition for Running the DTC
• DTCs P060B and P0651 are not set.
• The battery voltage is between 18 to 32 volts.
• The ignition switch is ON.
• The engine run time is longer than 3 minutes.
(DTC P0113)
Condition for Setting the DTC
• The ECM detects that the IAT sensor signal
voltage is less than 0.1 volts for 3 seconds. (DTC
P0112)
Circuit/ System Testing DTC P0112
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 P0651 also set?
Observe the Intake Air Temperature (IAT) Sensor
parameter with a scan tool.
3
Is the IAT Sensor parameter less than the specified
value?
1. Turn OFF the ignition.
2. Disconnect the mass air flow/ intake air
temperature (MAF/ IAT) sensor harness
connector (Euro 4 specification) or the IAT
sensor harness connector (expect Euro 4
4
specification).
3. Turn ON the ignition, with the engine OFF.
Is the IAT Sensor parameter more than the
specified value?
Action
• The ECM detects that the IAT sensor signal
voltage is more than 4.85 volts for 3 seconds.
(DTC P0113)
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 IAT 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 IAT 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 P0651
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