The trouble codes P0112 and P0113 both relate to issues with the Intake Air Temperature (IAT) sensor in a vehicle's engine. Each code indicates a different aspect of the IAT sensor's performance problem. Here's an overview of each code:
1. **P0112 - Intake Air Temperature Sensor Circuit Low Input:**
- This code is triggered when the Engine Control Module (ECM) detects that the signal from the Intake Air Temperature (IAT) sensor is lower than the expected range. This could indicate a low voltage input or a short to ground.
2. **P0113 - Intake Air Temperature Sensor Circuit High Input:**
- This code, on the other hand, is triggered when the ECM detects that the signal from the IAT sensor is higher than the expected range. This could indicate a high voltage input or a short to power.
### Common Causes for IAT Sensor Codes:
1. **Faulty IAT Sensor:** The IAT sensor itself may be malfunctioning or damaged.
2. **Wiring Issues:** Problems with the wiring, connectors, or the harness leading to the IAT sensor.
3. **Air Filter Issues:** A clogged or dirty air filter can impact the IAT sensor's performance.
4. **Intake System Issues:** Problems in the intake system, such as a leak or obstruction, can affect the IAT sensor readings.
### Diagnosing and Repair:
1. **Visual Inspection:** Inspect the IAT sensor wiring, connectors, and the sensor itself for any visible issues.
2. **Check Air Filter:** Ensure the air filter is clean and not obstructed.
3. **Inspect for Intake System Issues:** Check for obstructions or leaks in the intake system.
4. **Test IAT Sensor:** Use a multimeter to test the IAT sensor's resistance or voltage output, depending on the sensor type.
5. **Replace Faulty Components:** If issues are found, replace the faulty components, such as the IAT sensor or damaged wiring.
It's essential to note that the IAT sensor is often integrated into the Mass Air Flow (MAF) sensor in many modern vehicles. If you've already addressed MAF sensor issues (as indicated by the P0101, P0102, and P0103 codes), and you're still having problems, it may be worthwhile to inspect the IAT sensor as well.
If you're not comfortable with these diagnostic steps, it's recommended to seek assistance from a qualified mechanic or automotive technician to accurately identify and address the issue with the IAT sensor.