Oxygen Sensor Issue with P1133 Code in 2003 Isuzu Rodeo 6-Cylinder
I recently replaced the oxygen sensor for Bank 1 Sensor 1 (right side) on my 2003 Isuzu Rodeo 6-cylinder model, but the P1133 fault code has persisted after 2 to 3 months. The check engine light remains on even after the replacement. This issue has been recurring for over three years. I'm seeking advice on possible root causes and diagnostics.
Are there any other diagnostic trouble codes present? The Powertrain Control Module (PCM) is not detecting the oxygen sensor's normal signal transition—specifically, it should switch from a lean to a rich condition as engine load and mixture adjust. Using an OBD2 scanner to monitor the oxygen sensor signal can help identify if the sensor is functioning correctly. Potential causes include vacuum leaks maintaining a lean condition or leaking fuel injectors causing a rich condition. Exhaust leaks should also be ruled out.