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P0157 is a diagnostic trouble code (DTC) for "02 Sensor Circuit Low Voltage (Bank 2 Sensor 2)". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
Oxygen Sensor Circuit Low Voltage (Bank 2 Sensor 2)
The oxygen sensor that trouble code P0157 refers to, is located in the rear of the exhaust and behind the catalytic converter. It’s main function is to regulate the amount of oxygen that comes from the catalytic converter. A lean mixture of oxygen and gas means that there is too much oxygen in the exhaust. A rich mixture of oxygen and gas means that there is not enough oxygen in the exhaust.
Neither a lean mixture or rich mixture is good for the catalytic converter and both can cause premature failure of the catalytic converter. The oxygen sensor switches back and forth from low voltage (lean) to high voltage (rich). When this code is stored by the power control module (PCM), it means that the oxygen sensor has remained at a low voltage for too long.
Collects trouble code and views freeze frame data from the OBD-II scanner.
Also uses scan tool to monitor oxygen sensor voltage to see if it is switching properly.
If an engine coolant temperature sensor trouble code is present as well, view its live data to see if it is working properly.
Checks fuel pressure with fuel pressure gauge. Proper fuel pressure should be at 40 psi.
Inspects the exhaust for air leaks in the manifold and pipes.
Inspects the rear oxygen sensor wires for shorts, breaks or exposure.
The computer may need to be updated at the dealer.
Advance diagnosis may also be necessary to determine if there is a problem with the Primary Control Module (PCM).
The P0157 trouble code is considered moderately serious. It can cause drivability issues and has the potential of causing the car to stall out. If not addressed, damage to the catalytic converter can be done over time, which will be expensive to fix. It is recommended to have this problem addressed as soon as possible.
If the oxygen sensor has ceased up in the exhaust pipe, which is common, specialty tools will be required. An oxygen sensor set will make it easier to reach an oxygen sensor that is positioned awkwardly, and a propane torch is used as a heating element to assist in the removal.
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