A "high voltage" code related to the O2 sensor typically indicates a problem in the *wiring* leading to that sensor, not the sensor itself. The problem could be:
* Damaged wiring: A short circuit in the wiring harness running to sensor 2, bank 1 (the second sensor on the exhaust manifold after the catalytic converter). This wiring could be damaged anywhere along its route from the sensor to the PCM (Powertrain Control Module).
* Faulty PCM: A malfunctioning PCM might be sending an incorrect voltage signal.
* Connectors: Corrosion or a loose connection at either the sensor or the PCM end of the wiring harness.
To find the problem:
1. Obtain the specific diagnostic trouble code (DTC): This code, usually a P-code (e.g., P0138, P0158, etc., depending on which bank and sensor is affected), is crucial. A code reader is necessary to get this information. The code itself will help you pinpoint the exact sensor.
2. Consult a repair manual: A repair manual specific to your 1999 Jeep Wrangler 2.5L will show wiring diagrams for the O2 sensors. This will allow you to trace the wiring from the sensor to the PCM, checking for damage, shorts, or poor connections along the way.
3. Inspect the wiring harness visually: Carefully examine the wiring harness from the bank 1, sensor 2 O2 sensor back towards the engine and PCM, looking for any signs of damage, chafing, or melting. Pay close attention to areas where the wiring is close to hot exhaust components.
4. Check the O2 sensor connector: Inspect the connector at both the sensor and the harness for corrosion, loose connections, or broken wires.
5. Use a multimeter: A multimeter can be used to test the voltage and resistance of the wiring to ensure it's within specifications (as found in your repair manual).
In short, you won't find a single "location" for a high voltage O2 sensor circuit problem; you'll need to troubleshoot the entire electrical circuit. A repair manual and a multimeter are essential tools for this.
