P0156 OBD-II: O2 Sensor Circuit
P0156 Severity
Will P0156 go away on its own?
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.
What causes OBD-II fault code P0156?
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 P0156.
OBD II Fault Code
- OBD II P0156
Fault Code Definition
The Rear Catalyst Monitoring Oxygen Sensor evaluates the Catalytic Converter's emissions-reducing capability. Code P0156 is set when the Rear Oxygen Sensor signal does not show enough activity to indicate fuel control and closed loop fuel management.
P0156 Symptoms
- Check Engine Light will illuminate
- In many cases, no abnormal symptoms may be noticed
- In some cases, the vehicle will fail an Emissions Test
- In some cases, the NOx emissions will be elevated
Common Problems That Trigger the P0156 Code
- Defective Bank 2 Rear Oxygen Sensor
- Faulty Bank 2 Rear Oxygen Sensor wiring or connections
Common Misdiagnoses
- Oxygen Sensor is replaced when the problem is faulty sensor wiring or connections
- Rear Oxygen Sensor is replaced when the problem is an exhaust leak before the Rear Oxygen Sensor
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