1. Faulty IAT Sensor: It's possible that the replacement IAT sensor is defective or not properly installed. Check the sensor's electrical connection and make sure it's securely plugged in. You may also want to try cleaning the sensor or replacing it again.
2. Other Sensor Issues: The check engine light could be triggered by another faulty sensor or component related to the intake air temperature system. Common culprits include the mass air flow (MAF) sensor, throttle position sensor (TPS), or oxygen sensor. You should have the vehicle scanned for trouble codes again to identify any additional issues.
3. Wiring Problems: Check the wiring harness that connects the IAT sensor to the engine control unit (ECU). Make sure there are no loose connections, breaks, or shorts in the wiring. Any damage to the wiring can disrupt the signal between the sensor and the ECU, leading to incorrect readings and the check engine light.
4. Vacuum Leaks: A vacuum leak can affect the engine's air/fuel mixture and cause the IAT sensor to provide incorrect readings. Check the hoses, gaskets, and seals in the intake system for any leaks. A smoke test can be performed to identify any hard-to-find vacuum leaks.
5. ECU Issues: In rare cases, the problem could lie with the engine control unit (ECU) itself. The ECU processes the signals from various sensors and controls the engine's functions. If the ECU is faulty or experiencing internal problems, it can provide incorrect air/fuel mixture calculations and trigger the check engine light.
To accurately diagnose the cause of the check engine light, it's recommended to have a qualified mechanic or technician inspect the vehicle, review the trouble codes, and perform necessary tests to identify and fix the underlying issue.
