Opel Frontera UE. Manual - part 1519

6E–291

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC)

P1111 IAT Sensor Circuit Intermittent High Voltage

D06RY00147

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 is
lower causing the PCM to monitor a lower voltage. DTC
P1111 will set when the PCM intermittently detects an
excessively high signal voltage on the intake air
temperature sensor signal circuit.

Conditions for Setting the DTC

The engine has been running for over 30 seconds.

Vehicle speed is less than 32 km/h (20 mph).

Engine coolant temperature is above 60

C (140

F).

Mass air flow is less than 20g/second.

IAT signal voltage indicates and intake air temperature
intermittently less than –39

C (–38

F) (about 5 volts)

for approximately 2.5 seconds over a 25-second
period of time.

Action Taken When the DTC Sets

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

The PCM will store conditions which were present
when the DTC set as Failure Records data only. This
information will not be stored as Freeze Frame data.

DTC P1111 does not illuminate the MIL.

Conditions for Clearing the MIL/DTC

A history DTC P1111 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P1111 can be cleared by using the Tech 2 “Clear
Info” function.

Diagnostic Aids

Check for the following conditions:

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.

Damaged harness – Inspect the wiring harness for
damage. 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.

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6E–292

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.

Intake Air Temperature Sensor

OHMS

Temperature vs. Resistance Values

(approximate)

100

212

177

176

332

140

667

113

1188

1802

2796

4450

7280

–5

12300

–15

21450

–30

–22

52700

–40

100700

SECTION

6E–293

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

DTC P1111 –IAT Sensor Circuit Intermittent High Voltage

Step

Action

Value(s)

Yes

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

—

Go to

Step 2

Go to

OBD

System

Check

Is DTC P0113 also set?

—

Go to

DTC

P0113 chart

first

Go to

Step 3

Is DTC P1115, also set?

—

Go to

Step 6

Go to

Step 4

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 5

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 6

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 7

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 8

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 9

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

SECTION

6E–294

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC)

P1112 IAT Sensor Circuit Intermittent Low Voltage

D06RY00147

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. DTC P1112 will set when the PCM intermittently
detects an excessively low signal voltage on the intake air
temperature sensor signal circuit.

Conditions for Setting the DTC

The engine has been running for over 15 seconds.

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

IAT signal voltage is greater than 148

C (298

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

Action Taken When the DTC Sets

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

The PCM will store conditions which were present
when the DTC was set as Failure Records data only.
This information will not be stored as Freeze Frame
data.

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

Conditions for Clearing the MIL/DTC

A history DTC P1112 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P1112 can be cleared by using the Tech 2 “Clear
Info” function.

Diagnostic Aids

Check for the following conditions:

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.

SECTION

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