Isuzu Rodeo UE. Manual - part 234

6E1–307

RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

be set occurs. This may assist in diagnosing the
condition.

Intake Air Temperature Sensor

°

C

°

F

W

Temperature vs. Resistance Values (approximate)

100

212

177

80

176

332

60

140

667

45

113

1188

35

95

1802

25

77

2796

15

59

4450

5

41

7280

–5

23

12300

–15

5

21450

–30

–22

52700

–40

–40

100700

6E1–308

RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DTC P1111 – IAT Sensor Circuit Intermittent High Voltage

 

Step

Action

Value(s)

Yes

No

1

Was the ”On–Board Diagnostic (OBD) System Check”
performed?

—

Go to Step  2 

Go to OBD

System

Check 

2

Is DTC P0113 also set?

—

Go to DTC

P0113 chart

first 

Go to Step 3 

3

1. Check for a poor sensor ground circuit terminal

connection at the IAT sensor.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to Step 4 

4

1. Check for a poor IAT signal circuit terminal

connection at the IAT sensor.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to Step 5 

5

1. Check the IAT signal circuit between the IAT sensor

connector and the PCM for an intermittent open.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to Step 6 

6

1. Check the IAT signal circuit between the IAT sensor

connector and the PCM for an intermittent short to
voltage.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to Step 7 

7

1. Check for a poor sensor ground circuit terminal

connection at the PCM.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to Step 8 

8

1. Check for an intermittent open or a faulty splice in

the sensor ground circuit.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Refer to

Diagnostic

Aids 

6E1–309

RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DIAGNOSTIC TROUBLE CODE (DTC) P1112 INTAKE AIR TEMPERATURE (IAT)

SENSOR CIRCUIT INTERMITTENT LOW VOLTAGE

D06RX043

Circuit Description

The intake air temperature (IAT) sensor is a thermistor
which measures the temperature of the air entering the
engine. The powertrain control module (PCM) applies 5
volts through a pull–up resistor to the IAT sensor. When
the intake air is cold, the sensor resistance is high and the
PCM will monitor a high signal voltage on the IAT signal
circuit. If the intake air is warm, the sensor resistance
becomes lower, causing the PCM to monitor a lower
voltage. Diagnostic Trouble Code P1112 will set when the
PCM intermittently detects an excessively low signal
voltage on the intake air temperature sensor signal
circuit.  DTC P1112 is a type D code.

Conditions for Setting the DTC

f

The engine has been running for over 2 minutes.

f

Vehicle speed is greater than 48 km/h (30 mph).

f

IAT signal voltage is greater than 148

°

C (298

°

F)

(about 0.10 volt) for a total of 2.5 seconds over a
25–second period of time.

Action Taken When the DTC Sets

f

The PCM will not illuminate the malfunction indicator
lamp (MIL).

f

The PCM will store conditions which were present
when the Diagnostic Trouble Code set as Failure

Records data only. This information will not be stored
as Freeze Frame data.

f

The PCM will substitute a default value for intake air
temperature.

Conditions for Clearing the DTC

f

A history Diagnostic Trouble Code P1112 will clear
after 40 consecutive warm–up cycles have occurred
without a fault.

f

Diagnostic Trouble Code P1112 can be cleared by
using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

Check for the following conditions:

f

Poor connection at PCM – Inspect harness connectors
for backed–out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal–to–wire connection.

f

Damaged harness – Inspect the wiring harness for
damage; shorts to ground, shorts to battery positive,
and open circuits. If the harness appears to be OK,
observe the IAT display on the Tech 2 while moving
connectors and wiring harnesses related to the IAT
sensor. A change in the IAT display will indicate the
location of the fault.

Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the Diagnostic Trouble Code to

6E1–310

RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

be set occurs. This may assist in diagnosing the
condition.

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Verifies that the fault is present.

3. If DTC P1112 can be repeated only by duplicating

the Failure Records conditions, refer to the
”Temperature vs. Resistance Value Chart.” 

The chart may be used to test the IAT sensor at
various temperatures to evaluate the possibility of
a ”shifted” sensor that may be shorted above or
below a certain temperature. If this is the case,
replace the IAT sensor.

Intake Air Temperature Sensor

°

C

°

F

W

Temperature vs. Resistance Values (approximate)

100

212

177

80

176

332

60

140

667

45

113

1188

35

95

1802

25

77

2796

15

59

4450

5

41

7280

–5

23

12300

–15

5

21450

–30

–22

52700

–40

–40

100700

DTC P1112 – IAT Sensor Circuit Intermittent Low Voltage

 

Step

Action

Value(s)

Yes

No

1

Was the ”On–Board Diagnostic (OBD) System Check”
performed?

—

Go to Step  2 

Go to OBD

System

Check 

2

Is DTC P0112 also set?

—

Go to DTC

P0112 chart

first 

Go to Step  3 

3

1. Check the IAT signal circuit between the IAT sensor

connector and the PCM for an intermittent short to
ground.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Refer to

Diagnostic

Aids