Error P0156 – how to fix?

Error code definition P0156

Oxygen Sensor Circuit Malfunction (Bank Sensor 2)

What does the code P0156 mean

The task of the oxygen sensor is to monitor the amount of oxygen present in the exhaust gas and report this information to the Power Control Module (PCM). As the amount of oxygen increases or decreases, the oxygen sensor oscillates between low and high voltage.

If the oxygen sensor remains at low voltage for an extended period of time or is simply not active at all, the power control module (PCM) will write error code P0156 and the Check Engine light will illuminate to indicate to the driver that there is a problem with the engine.

What causes the code P0156?

• Exhaust gas leaks
• Intake air leaks
• Faulty fuel injectors
• Damaged or exposed wires
• Shorted voltage cables or circuits
• Exhaust vents near or around the oxygen sensor
• Vacuum leaks in the engine
• The oxygen sensor hoses are touching the exhalation

What are the symptoms of the P0156 code?

Drivers may not notice any symptoms related to fault code P0156. The Check Engine light will come on, which is the most noticeable symptom, and you may lose fuel economy. The vehicle will also have an increased emission of pollutants into the environment.

How does the mechanic diagnose the P0156 code?

• The OBD-II Scanner is used to record all fault codes that have been written by the Power Control Module (PCM).
• The live data from the oxygen sensor on the OBD-II scanner is reviewed to observe that the oxygen sensor is functioning properly.
• They will be able to draw conclusions, paying attention to whether the oxygen sensor switches from low voltage to high voltage as it should.
• When using an OBD-II scanner, they will see live data from the fuel injectors to make sure they are working properly.
• The oxygen sensor wiring will be checked for short circuits, damage or exposed wires.
• Check the engine for air leaks. This could indicate vacuum leaks or damaged vacuum lines, then the exhalation will be checked for holes.

The most common errors when diagnosing the P0156 code

• The most common error in diagnosing fault code P0156 is automatically replacing the oxygen sensor without checking other components. The oxygen sensor is not always a problem, and replacing the oxygen sensor does not always fix the problem.
• Consider the condition of the wiring, exhaust system, vacuum lines, intake and fuel injectors.

How serious is the P0156 code?

This code is generally not considered to be serious. However, the driver may experience increased fuel consumption, and in this state the vehicle will release more pollutants into the environment.

What repairs can fix the P0156 code?

• Repair shorted, broken, or exposed oxygen sensor wires
• Repair vacuum leaks
• Repair the holes in the exhaust system or replace the exhaust system if necessary.
• Replace the fuel injector if it is damaged
• Replace oxygen sensor (bank sensor 2)

Additional notes regarding code P0156

Sometimes, depending on the vehicle, the oxygen sensor may be difficult to access. An oxygen sensor kit may be required to remove the sensor. It is also common for the oxygen sensor to become stuck in the exhaust pipe and must be properly removed with a heating element such as a propane burner, in addition to the oxygen sensor kit.