Error Code P0152: O2 Sensor Circuit High Voltage (Bank 2 Sensor 1)

Error Code P0152 is defined as Oxygen Sensor Circuit High Voltage Bank 2 Sensor 1. This trouble code occurs when there’s excessively high voltage from the sensor sent to the PCM (powertrain control module, also referred as ECM or engine control module in other makes).

This code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II, made 1996 to present. Specifications for definition and troubleshooting however, depends on the make and model of the vehicle.

Definition

The job of the Oxygen (O2) sensor is to measure the oxygen content in the exhaust. The PCM will then use that data to regulate the pulse of the fuel injector. The O2 sensor plays an important role for the engine’s proper operation. Any problem with it can cause the PCM to add or take away too much fuel as it doesn’t receive the right information from the O2 sensor voltage.

This code’s purpose is to track the time the Air Fuel Ratio sensor or O2 sensor takes to go from determining the fuel control system is in an open loop to rapidly switch over and below 450-millivolt set point, indicating the fuel control system is in closed loop. Therefore, the Error Code P0152 is set when there is a sustained high voltage signal from the O2 sensor for a specified amount of time, or the sensor was stuck too high or too low in rich position for too long.

Common Symptoms

As with other error codes, Error Code P0152 activates the Check Engine light and in some cases, abnormal symptoms can be hard to notice. Emission of course, is elevated. Other symptoms include:

  • Engine runs lean when testing the sensor
  • The PCM will lean the mixture as it tries to correct the rich problem, causing it to misfire or hesitate
  • Lack of power
  • Engine running rough
  • Excessive fuel consumption

Possible Causes

Possible causes for this error code include:

  • Rich engine and O2 sensor
  • Faulty Bank 2 Sensor 1 O2 sensor which sends incorrect rich condition reading
  • Signal shorted to voltage in harness
  • Damaged wiring harness (commonly leads to melted wires due to exhaust components)
  • Leaking injectors
  • Vacuum leaks (leading to lean condition)
  • Faulty fuel pressure injector
  • Bad PCM (rare)

How to Check

This error code is diagnosed by scanning the codes and documenting the freeze frame data, and then clearing the codes to check whether it returns.

If the code indeed returns, mechanics would usually monitor the oxygen sensor data to check whether the voltage is stuck at or above 1.2V. If it is stuck, they will proceed to disconnect the sensor and see whether the voltage goes down to zero and then replace the sensor with a new one.

If the voltage is shorted with the sensor, you can disconnect it and then check the oxygen sensor wiring and the harness connections for signs of damage, such as burned wires and cuts, and then repair as needed.

How to Fix

The fix for this error code is pretty straightforward. If through your diagnosis you have determined that the O2 sensor for bank 2 sensor 1 is at fault, then you should replace it.

  • Burned or shorted wiring and connectors should be repaired.
  • Leaks in the injector or fuel pressure regulator should be fixed.

If you are experiencing lean or rich codes associated with this error code, then you should first focus on fixing those problems first, as they can cause the O2 sensor voltage readings to appear faulty when they are in fact, only reading it correctly.

The O2 sensor’s high voltage output may just be an over rich condition from a leaking or stuck open injector.

The PCM may not have the ability to control the air-fuel mixture if there is a leak in the fuel system or the oxygen sensor is shorted.

 

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