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Oxygen Sensor Circuit Low Voltage (Bank 2, Sensor 2)
P0157 is a generic OBD-II code, which means that the oxygen sensor in bank 2, sensor 2, has a low voltage signal. The low voltage is caused by a bad or corroded oxygen sensor, but it could also be caused by a bad wiring connection to the sensor or an open circuit somewhere in between where you have power going to both sides of that connection.
As the name suggests, the check engine light is triggered when there is a problem with your car’s emissions system. It can be any of these symptoms:
The P0157 code is triggered when the PCM detects an oxygen sensor voltage that is too low at a high engine load or when it detects an intermittent failure of one of the oxygen sensors in Bank 2.
This means a problem with your car’s electrical system related to the oxygen sensor circuit for Bank 2 and Sensor 2. Your vehicle has two banks of cylinders, and each bank has its own set of four oxygen sensors: one for each cylinder in that bank. When you have this issue, something could be wrong with your wiring harness or plug connector, which connects to your ECU (electronic control unit). This could also happen if you had a bad ground connection somewhere else on your vehicle, such as at a battery post or starter motor mount bracket bolts, which both use sheet metal screws instead plastic ones like most other things do because they don’t rust over time like metal ones do when exposed directly outdoors where salt air can get inside them causing corrosion issues over time as well.
The first thing to do is check if the oxygen sensor is dirty or damaged. If it’s not, then you need to check the wiring harness of your car and see if there are any loose connection points or damaged wires. Sometimes they can be hard to spot, so make sure that everything is connected as firmly as possible before moving on with this diagnosis process. If everything looks good, then you’ll need to check the ECU itself. This can be done by removing it from your car and taking it to a mechanic for testing.