P0113
DTC P0113 Intake Air Temperature (IAT) Sensor Circuit High Voltage
Circuit Description
The intake air temperature (IAT) sensor is a thermistor. The control module (PCM/VCM) supplies the IAT sensor a reference voltage on the IAT sensor signal circuit and a ground circuit. When the IAT sensor resistance is high (cold sensor), the IAT sensor signal voltage remains near the supplied voltage, and decreases the signal voltage as the sensor warms. The control module monitors the IAT sensor signal circuit in order to calculate the temperature of the air entering the engine.
This DTC is designed to detect an IAT sensor signal voltage higher than the possible range of a normally operating IAT sensor.
Conditions for Running the DTC
- No active ECT sensor DTCs
- No active VS sensor DTCs
- No active MAF sensor DTCs
- The vehicle speed less than 2 mph (3 kph)
- The MAF is less than 250 g/s
- The engine coolant temperature is greater than 85°C (185.5° F)
- The engine run time is greater than 100 seconds
Conditions for Setting the DTC
The AT voltage is above 4.9 V for more than 5 seconds.
Action Taken When the DTC Sets
- The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive key cycles.
- The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tool's Freeze Frame and Failure Records.
Conditions for Clearing the MIL/DTC
- The control module turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed
- A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm up cycle occurs when the coolant temperature has risen 22° C (40° F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70° C (158° F) during the same ignition cycle.
- Use the scan tool Clear Information function
Diagnostic Aids
The IAT sensor indicates the temperature of the ambient air which is entering the throttle body. The IAT sensor temperature should read very close to the temperature of the outside air. The air temperature should rise gradually as the engine warms up and the underhood temperature increases. If DTC P1111 is set, the problem is intermittent. Check for an open in the IAT sensor circuit. This may be accomplished by moving the VCM harness at various locations and monitoring the IAT temperature or IAT voltage on the scan tool. If the voltage varies, look for an open in the area of the harness that caused the variance. Also, a sensor may become skewed or mis-scaled. The Temperature vs. Resistance table will help in order to detect a skewed sensor. Refer to Temperature vs Resistance.
An intermittent may be caused by any of the following conditions
- A poor connection
- Rubbed through wire insulation
- A broken wire inside the insulation
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent and Poor Connections.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs.
Steps 1 - 2:
Steps 3 - 8:
Steps 9 - 13:
Steps 14 - 15:
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Important: Use the same diagnostic test equipment for all the measurements.
2. If the IAT sensor circuit voltage measures more than 4.9 volts, the conditions for the DTC are still present, and the problem is not intermittent.
3. This test will bypass the IAT sensor and will confirm that the IAT signal circuit and the sensor ground circuit to the VCM are sound. Grounding the IAT sensor signal circuit will provide a low voltage input to the VCM. The VCM should recognize this low voltage and indicate a high IAT temperature.
4. This test determines if the IAT sensor signal circuit is okay. If the scan tool does not indicate a high IAT temperature, the IAT signal circuit is open.