What does code P0139 mean on a 2004 Jeep Liberty Limited?

Answer 1

Code P0139 on a 2004 Jeep Liberty Limited indicates a problem with the oxygen sensor circuit, specifically that the signal from the O2 sensor is fluctuating too slowly, or the sensor is not responding properly. This typically points to a malfunctioning O2 sensor, an exhaust leak, or issues with the wiring and connectors associated with the sensor. It can lead to poor fuel economy and increased emissions if not addressed. It's advisable to inspect and potentially replace the O2 sensor or check for other related issues.