1. Locate the IAT Sensor:
* The IAT sensor on a 1999 Cavalier is typically located in the intake air duct, somewhere between the air filter box and the throttle body. It's a small, usually two-wire sensor. Consult your car's repair manual for the exact location; a diagram will be invaluable.
2. Visual Inspection:
* Check the sensor connector: Carefully inspect the connector for any signs of damage, corrosion, loose wires, or broken pins. Clean the connector with electrical contact cleaner if necessary. Make sure the connector is securely plugged in. A loose connection is a common culprit.
* Inspect the wiring: Follow the wires leading from the sensor to the engine control module (ECM). Look for any damage to the wiring harness, such as fraying, cuts, or melted insulation.
3. Testing the IAT Sensor (Requires a Multimeter):
* Disconnect the sensor: Unplug the connector from the sensor.
* Check for continuity: With the multimeter set to ohms, test the resistance between the two wires of the sensor. The resistance should change with temperature. A cold sensor will show higher resistance, while a warm sensor will show lower resistance. The exact resistance values should be specified in your repair manual or online resources for your specific vehicle. A sensor with no resistance or infinite resistance is likely faulty.
* Check for short circuits: With the multimeter set to ohms, check for continuity between each wire and ground. There should be no continuity. Continuity indicates a short.
* Check sensor voltage (if possible): With the engine running, some multimeters can measure the voltage being supplied to the IAT sensor. The voltage reading should be within the specification provided in your service manual (if available). This helps determine if the issue is with the sensor itself, or the circuit supplying power to the sensor.
4. Possible Solutions Based on Testing:
* Loose or corroded connector: Clean the connector and ensure it's securely plugged in.
* Damaged wiring: Repair or replace any damaged wiring.
* Faulty IAT sensor: Replace the IAT sensor. This is the most likely solution if the sensor tests faulty. These sensors are relatively inexpensive and readily available at auto parts stores.
* Other issues (less likely): If the wiring and sensor are good, the problem could lie with the ECM itself, although this is less common.
Important Notes:
* Repair Manual: A repair manual specific to your 1999 Chevy Cavalier is highly recommended. It will provide detailed diagrams, specifications, and troubleshooting procedures. You can usually find these online (e.g., Haynes or Chilton manuals) or at auto parts stores.
* Safety: Disconnect the negative battery cable before working on any electrical components.
* Professional Help: If you're not comfortable working on your car's electrical system, it's best to take it to a qualified mechanic.
Replacing the IAT sensor is usually the most effective solution for a P0113 code. But systematic troubleshooting, starting with the simple checks, saves time and money. Remember to clear the code with an OBD-II scanner after making repairs to verify the fix.
