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P0140 Severity
Once the vehicle's onboard system no longer detects the issue, most codes will disappear on their own. If your vehicle still has this code, however, it should be properly diagnosed to avoid a more serious problem.
For a proper diagnosis, RepairPal Certified shops have the equipment, tools, and expertise.
Moderate severity codes might not threaten the vehicle's safety or functionality immediately, but you should still get it diagnosed within a reasonable time frame to keep your car running well.
The purpose of the oxygen sensor is to measure the oxygen content in the exhaust gases after they leave the combustion process of the engine. This information is critical to the PCM's ability to maintain efficient fuel economy. When the PCM detects a failure of the sensor or the information received from the sensor, it will set code P0140.
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The Catalyst Monitoring Oxygen Sensor evaluates the rear most Catalytic Converter's emissions-reducing capability. Code P0140 is set when there is no activity in the signal from the Rear Oxygen Sensor.