<ul> <li><b>Engine Light ON (or Service Engine Soon Warning Light)</b>: The illumination of the engine light indicates a detected issue with the O2 sensor positive current control circuit. This can be caused by a malfunctioning O2 sensor, wiring issues, or a faulty Engine Control Module (ECM).</li> <li><b>Poor Fuel Economy</b>: A malfunctioning O2 sensor can lead to incorrect air-fuel mixture readings, causing the engine to run rich or lean, which negatively impacts fuel efficiency.</li> <li><b>Rough Idle</b>: An improper air-fuel mixture due to a faulty O2 sensor can cause the engine to idle roughly, leading to vibrations and unstable engine performance.</li> <li><b>Increased Emissions</b>: A defective O2 sensor can result in higher emissions due to improper combustion, potentially causing the vehicle to fail emissions tests.</li> </ul>

<ul><li>The front heated oxygen sensor on Bank 1 may be faulty, leading to incorrect readings and triggering the error code.</li><li>An open or shorted harness in the front heated oxygen sensor on Bank 1 can disrupt the sensor's functionality.</li><li>Poor electrical connections in the front heated oxygen sensor circuit on Bank 1 can cause intermittent or incorrect signals.</li></ul>

<ul> <li><b>Retrieve Stored Codes and Freeze Frame Data</b>: Connect the diagnostic scanner to the vehicle's diagnostic port. Retrieve all stored codes and pertinent freeze frame data. Document this information for future reference.</li> <li><b>Clear Codes and Test Drive</b>: Clear the codes and test drive the vehicle. Observe if the code P2239 is reset or if the PCM enters readiness mode. If the code is intermittent, it may not reset immediately.</li> <li><b>Perform Visual Inspection</b>: Inspect the HO2S related wiring and connectors for any signs of damage such as cuts, burns, or corrosion. Replace any damaged wiring or connectors.</li> <li><b>Check Resistance with DVOM</b>: Unplug the HO2S in question. Use a digital volt/ohmmeter (DVOM) to check resistance between the positive current control circuit and any ground circuits. If there is continuity, suspect a defective HO2S.</li> <li><b>Observe Oxygen Sensor Data</b>: Start the engine and allow it to reach normal operating temperature. Connect the scanner and observe the oxygen sensor input data. Pre-cat sensors should cycle between 1 and 900-millivolts. Post-cat sensors should also cycle but remain relatively stable.</li> <li><b>Check HO2S Voltage</b>: If the HO2S displays battery voltage or no voltage on the scanner data stream, use the DVOM to obtain live data from the HO2S connector. If the output data remains the same, suspect an internal HO2S short.</li> <li><b>Replace Defective HO2S</b>: If all tests point to a defective HO2S, replace the sensor. Clear the codes and perform a final test drive to ensure the issue is resolved.</li></ul>

<p>The DTC code P2239 indicates an issue with the O2 Sensor Positive Current Control Circuit High for Bank 1 Sensor 1. This is a moderate issue.</p><ul><li><b>Immediate Actions:</b> Inspect the O2 sensor wiring and connections for damage or corrosion.</li><li>Check the sensor itself for proper operation.</li><li>Replace the sensor if necessary.</li></ul><p>Delaying repair can lead to poor fuel economy and increased emissions.</p>