Definition of error code P0156
Fault in oxygen sensor circuit (bank 2 sensor)
What code P0156 means
The function of the oxygen sensor is to monitor the amount of oxygen present in the exhaust gases and transmit this information to the power control module (PCM). When 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, the power control module (PCM) will register the error code P0156 and the Check Engine light will illuminate to indicate to the driver that there is an engine problem.
What causes the P0156 code?
- Exhaust gas leak
- Intake Air Leaks
- Defective fuel injectors
- Damaged or exposed hoses
- Shorted wires or voltage circuits
- Exhaust holes near or around oxygen sensor
- Engine vacuum leaks
- Oxygen sensor wires are touching the exhaust
What are the symptoms of code P0156?
Drivers may not notice any symptoms associated with the P0156 trouble code. The Check Engine light comes on, which is the most noticeable symptom, and there may be a loss of fuel economy. The vehicle will also have increased emissions to the environment.
How does a mechanic diagnose a P0156 code?
- The OBD-II scanner is used to record all the fault codes that have been recorded by the power control module (PCM).
- The live data from the oxygen sensor in the OBD-II scanner is analyzed to observe if the oxygen sensor is working properly.
- You can draw conclusions by observing whether the oxygen sensor switches from low voltage to high voltage, as it should.
- Using the 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.
- The engine shall be checked for air leaks. This may indicate vacuum leaks or damaged vacuum lines, and the exhaust will be checked for holes.
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 the problem, and replacing the oxygen sensor does not always solve the problem.
- Consider the condition of the wiring harness, exhaust system, vacuum lines, fuel inlet, and fuel injectors.
How serious is the P0156 code?
This code is not generally considered serious. However, the driver may experience increased fuel consumption and, in this condition, the vehicle will release more pollutants into the environment.
What repairs can repair a P0156 code?
- Repair of shorted, interrupted or exposed oxygen sensor cables
- Repair vacuum leaks
- Repair holes in the exhaust system or replace the exhaust system if necessary.
- Replace the fuel injector if it is damaged
- Replace the oxygen sensor (sensor bank 2)
Additional notes on 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 get stuck in the exhaust pipe and have to be properly removed using a heating element, such as a propane torch, in addition to the oxygen sensor kit.
