DTC P0112 Intake Air Temperature (IAT) Sensor Circuit Low Voltage. Cadillac Seville 2000

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2000 🢒 Seville 🢒 DTC 🢒 DTC P0112 Intake Air Temperature (IAT) Sensor Circuit Low Voltage

Engine Controls Component Views
MAF and IAC
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The intake air temperature sensor is a thermistor (a variable resistor) that measures the temperature of the air entering the engine. The PCM supplies 5 volts to the IAT signal circuit through a pull-up resistor. When the intake air is cold, the PCM detects a high voltage on the IAT signal circuit. As the intake air warms, the PCM detects a lower voltage on the IAT signal circuit. If the PCM detects an excessively low IAT signal voltage (high temperature indicated), DTC P0112 will set.

Conditions for Running the DTC

•	ECT sensor, MAF sensor, or VSS DTCs are not set.

•	Engine has been running for at least 10 seconds.

•	Engine coolant temperature is below 100°C (212°F).

•	Vehicle speed is more than 15 km/h (9 mph).

Conditions for Setting the DTC

•	The IAT sensor signal voltage is less than 0.08 volt. This would be approximately 137°C (278°F).

•	The condition exists for less than 1 second.

Action Taken When the DTC Sets

•	The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test runs and fails.

•	The PCM stores the conditions present when the DTC set as Freeze Frame/Failure Records data.

Conditions for Clearing the MIL/DTC

•	The PCM will turn the MIL OFF after the third consecutive trip in which the diagnostic runs and passes.

•	The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

•	The DTC can be cleared by using the scan tool Clear DTC Information function.

Diagnostic Aids

For intermittent conditions, refer to DTC P1112 Intake Air Temperature (IAT) Sensor Circuit Intermittent Low Voltage and/or Symptoms .

Step	Action	Values	Yes	No
1	Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Connect the scan tool. Turn ON the ignition with the engine OFF. Observe the IAT sensor display. Does the scan tool indicate an intake air temperature more than the specified value?	125°C (257°F)	Go to Step 4	Go to Step 3
3	Review and record the scan tool Fail Records data. Operate the vehicle within the Fail Records conditions. Using the scan tool, monitor the Specific DTC Information for DTC P0112 until the test runs. Does the scan tool indicate that DTC P0112 failed last test?	--	Go to Step 4	Go to Diagnostic Aids
4	Turn OFF the ignition. Disconnect MAF/IAT sensor connector. Turn ON the ignition. Does the scan tool indicate an intake air temperature near the specified value?	-40°C (-40°F)	Go to Step 6	Go to Step 5
5	Turn OFF the ignition. Disconnect the PCM connector. Test the IAT sensor signal circuit for a short to chassis, the IAT sensor ground, or the MAF sensor ground. If a conditions is found, repair as necessary. Refer to Wiring Repairs in the Wiring Systems. Did you find and correct the condition?	--	Go to Step 8	Go to Step 7
6	Replace the IAT sensor. Refer to Mass Airflow Sensor/Intake Air Temperature Sensor Replacement . Is the action complete?	--	Go to Step 8	--
7	Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete?	--	Go to Step 8	--
8	Review and record the scan tool Fail Records data. Operate the vehicle within the parameters listed in the Conditions for Running the DTC. Using the scan tool, monitor the Specific DTC Information for DTC P0112 until the test runs. Does the scan tool indicate that DTC P0112 passed?	--	System OK	Go to Step 2