Possible causes for the P0136 code in your 1999 Hyundai Elantra could include:
1. Faulty O2 Sensor (Bank 1, Sensor 2): The O2 sensor itself may have failed or become defective, leading to inaccurate readings or no signal being sent to the Engine Control Unit (ECU).
2. Wiring Issues: The electrical wiring connecting the O2 sensor to the ECU could have loose connections, breaks, or shorts, causing disruptions in signal transmission.
3. O2 Sensor Circuit Issues: There may be problems within the circuit associated with the O2 sensor, such as poor grounding, corrosion, or damage to the wiring harness.
4. ECU Problems: In rare cases, the issue might lie within the ECU, where it fails to interpret or process the signals received from the O2 sensor correctly.
To accurately diagnose the root cause of the P0136 code in your vehicle, it's essential to perform further tests and inspections, such as examining the O2 sensor's condition, checking electrical connections, and using diagnostic tools to monitor O2 sensor readings and signals. If DIY diagnostics and repairs are challenging or beyond your expertise, it's advisable to consult a professional mechanic or take your vehicle to a reputable automotive service center for proper diagnosis and repair.
