P0112-INTAKE AIR TEMPERATURE SENSOR CIRCUIT LOW

For a complete wiring diagram Refer to Section 8W

When Monitored:
With the ignition on and battery voltage greater than 10.4 volts.
Set Condition:
The PCM detects that the Intake Air Temperature Sensor input voltage is below the minimum acceptable value.

Possible Causes

INTERMITTENT DTC

(K21) IAT SIGNAL CIRCUIT SHORTED TO GROUND

(K21) IAT SIGNAL CIRCUIT SHORTED TO (K915) SENSOR GROUND

(K21) IAT SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE

INTAKE AIR TEMPERATURE SENSOR

POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Diagnostic Test

1. DTC IS ACTIVE

Start the engine and allow it to reach normal operating temperature.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

Go to 2

Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

2. (K21) IAT SIGNAL CIRCUIT SHORTED TO GROUND

Turn the ignition off.
Disconnect the Intake Air Temperature Sensor connector.
Disconnect the Powertrain Control Module (PCM) connector.
Measure the resistance between ground and the (K21) IAT Signal circuit in the Intake Air Temperature Sensor harness connector.

Is the resistance above 100 ohms?

Yes

Go to 3

Repair the (K21) IAT Signal circuit for a short to ground.
Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).

3. (K21) IAT SIGNAL CIRCUIT SHORTED TO (K915) SENSOR GROUND CIRCUIT

Measure the resistance between the (K21) IAT Signal circuit and the (K915) Sensor Ground circuit in the Intake Air Temperature Sensor harness connector.

Is the resistance above 100 ohms?

Yes

Go to 4

Repair the (K21) IAT Signal circuit for a short to the (K915) Sensor Ground circuit.
Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).

4. (K21) IAT SIGNAL CIRCUIT OPEN CIRCUIT OR HIGH RESISTANCE

Measure the resistance of the (K21) IAT Signal circuit between the Intake Air Temperature Sensor harness connector and the Powertrain Control Module (PCM) harness connector.

Is the resistance below 5.0 ohms?

Yes

Go to 5

Repair the (K21) IAT Signal circuit for an open circuit or high resistance.
Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).

5. INTAKE AIR TEMPERATURE SENSOR

Turn the ignition off.
Connect the Powertrain Control Module (PCM) connector.
Turn the ignition on.
With the scan tool, read the Intake Air Temperature Sensor signal voltage.

Is the voltage above 4.5 volts with the Intake Air Temperature Sensor harness disconnected?

Yes

Replace the Intake Air Temperature Sensor in accordance with the service information.

Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).

Go to 6

6. POWERTRAIN CONTROL MODULE (PCM)

Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Intake Air Temperature Sensor and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
Look for the data to change or for the DTC to reset during the wiggle test.
Refer to any Technical Service Bulletins that may apply.

Were any problems found?

Yes

Repair as necessary.

Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).

Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information.
Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).