Error code P0113 indicates that the computer has received a high voltage signal from the intake air temperature sensor. This code will occur when the powertrain control module (PCM) receives a voltage of 5 volts or more from the IAT. This indicates a problem between the IAT and the PCM.

Definition

The vehicle’s PCM, or computer, sends a consistent reference voltage of about 5 volts to the IAT. Because it is a thermistor, the IAT resists that charge based on its temperature and the resulting voltage is returned to the PCM. The PCM uses this information to adjust such things as the air/fuel mixture and EGR valve.

If the IAT sends a voltage to the PCM that is in excess of 5 volts, the PCM returns the P0113 code. This error code is specific to voltage and will not be set if the IAT is simply returning unusual readings.

Common Symptoms

  • Check Engine Light Appears
  • Air/Fuel Mixture is Too Lean or Too Rich
  • Idles Poorly When Cold
  • Faulty EGR Valve Operation
  • Poor Fuel Economy
  • Increased Emissions

Possible Causes

  • The IAT is corroded or defective
  • Backfiring has occurred in the intake manifold
  • The tip of the sensor has been contaminated by oil
  • A wiring connector has corroded or detached
  • The IAT circuit has been shorted
  • The PCM has failed

What to Check

If the check engine light appears, use an OBD-II scanner to assess the error code. If it returns a P0113 error, there are a few things to examine.

Check the Air Temperature Reading

Allow the engine to run until it is warm. Use a scan gauge to compare the air temperature reading to the coolant temperature. Typically, a functional IAT sensor will report a slightly lower temperature than the coolant temperature sensor.

Examine Wiring Between the PCM and IAT

This error can be caused by wiring that has come loose or corroded, so examine the physical circuit between the IAT and the vehicle’s computer.

Test the Resistance

First, remove the IAT from the vehicle. Using an ohmmeter, measure the resistance of the IAT at room temperature. Then apply heat to the IAT sensor tip with a hair dryer and check to see if the resistance has decreased. No change in resistance or an infinite resistance reading indicate that the IAT sensor is faulty.

How to Fix It

Because a P0113 code is most frequently caused by either a dysfunctional circuit or a failed IAT sensor, the most common repair is simply replacing the faulty component. You can also try cleaning the IAT sensor tip and replacing the grounds.

Replacement IAT sensors are not usually very expensive, so replacing one is not a costly repair. Furthermore, a P0113 error may very rarely indicate a problem with the PCM. After you’ve fixed the IAT, clear the error codes and run the vehicle. If the P0113 code reappears, that could indicate a faulty PCM.