P0158 trouble code definition

Oxygen Sensor Circuit High Voltage (Bank 2 Sensor 2)

What the P0158 code means

The P0158 trouble code appears when the sensor has remained at a high voltage for too long.

This oxygen sensor is located behind the catalytic converter. It sends information to the power control module (PCM) about the efficiency and released oxygen levels of the catalytic converter.

When an engine is running lean, it means that there is more oxygen than fuel in the exhaust gases. When the engine is running rich, it means that there is more fuel than oxygen in the exhaust gases.

If the sensor is working properly it switches from low voltage (high levels of oxygen) to a high voltage (low levels of oxygen).

What causes the P0158 code?

  • Failed rear oxygen sensor
  • Failed rear oxygen sensor heater circuit
  • Engine coolant temperature sensor bad
  • Shorts, breaks, or exposed oxygen sensor wiring
  • Excessive fuel pressure
  • Necessary power control module (PCM) update
  • Failure of the power control module (PCM)

What are the symptoms of the P0158 code?

  • Check Engine Light will come on
  • Decreased fuel economy
  • Engine runs rough
  • Engine idles rough
  • Engine stalls

How does a mechanic diagnose the P0158 code?

  • A mechanic will use an OBD-II scanner to pull all present trouble codes that have been stored by the power control module (PCM).

  • The live data for the oxygen sensor on the scanner is reviewed. They will check the voltage reading to see if the oxygen sensor switches from low voltage to high voltage every few seconds.

  • When an engine coolant temperature sensor trouble code is present as well, the live data on the scanner is checked for proper engine temperature.

  • The wiring of the rear oxygen sensor is checked for shorts, breaks, or exposure.

  • Test the fuel pressure to see if it is higher than normal.

  • Run manufacturer diagnosis procedures on the power control module (PCM) to determine whether it needs to be replaced or updated.

Common mistakes when diagnosing the P0158 code

  • Replacing the oxygen sensor before considering other necessary repairs
  • Not properly expecting the wires for any shorts, breaks, or exposure

How serious is the P0158 code?

The P0158 trouble code is considered serious if it is causing the car to stall out. This problem should be addressed as soon as possible to avoid drivability issues.

What repairs can fix the P0158 code?

  • Replace the rear oxygen sensor
  • Repair any oxygen sensor wires that have shorted out, are broken or exposed
  • Make necessary repairs to remedy the excessive fuel pressure.
  • Replace engine coolant temperature sensor if it is necessary
  • Replace or update power control module (PCM), if necessary

Additional comments for consideration regarding the P0158 code

An oxygen sensor set and propane tank will be necessary to remove the oxygen sensor if it has ceased in the exhaust or is difficult to reach.

Need help with a P0158 code?

YourMechanic offers certified mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

This article originally appeared on YourMechanic.com as P0158 OBD-II Trouble Code: 02 Sensor Circuit High Voltage (Bank 2, Sensor 2) and was authored by Jamahl Walker.


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