P0158 Fault Code

Long Description

Fault code P0158 is logged when the engine control unit (ECU) has detected a high voltage signal from an oxygen sensor. This code specifically relates to the bank 2 oxygen sensor 2.

This error occurs when the output signal from the oxygen sensor is greater than 1.2 V for a period of 10 seconds or more. This is indicative of a lack of oxygen in the exhaust.

Bank 2 refers to the side of the engine that is opposite the location of the number 1 cylinder. This is only applicable for V-shape engines. For this fault code straight engines, see P0138.

A faulty sensor can cause the vehicle to run improperly as the ECU is being fed incorrect information. In this instance, the information helps determine the fuel injection process.

As mentioned, this fault code is only applicable to engines with two banks. This can put manufacturers like Chevrolet, Chrysler, and Jeep as the most synonymous brands for this fault code.

Other Signs of This Problem

The various signs of fault code P0158 are related to the running of the engine as the ECU is being given too little or incorrect information from the sensor.

The Check Engine light is one of the most obvious signs.

Other issues can be how the car runs. It is possible the vehicle will have a rough idle.

Additionally, the engine will run rich. This can lead to black smoke from the exhaust. It can also cause a decrease in fuel economy and performance.

For additional information, look out for codes between P0156 and P0161.

What Could Be The Problem?

Most of the potential causes are entirely related to the electrical components and circuitry due to the nature of a high voltage issue.

One of the most likely issues is a faulty downstream oxygen sensor. This will obviously provide an incorrect reading that can signal the fault code to be logged.

Additionally, there could be an issue with the wiring or connections. A frayed or damaged wire can disrupt the signal being sent.

This can also happen as a result of an open or short circuit in the wiring.

Other system errors like excessive fuel pressure can also lead to this issue.

Fixes

All of the fixes for P0158 are focused on fixing any existing electrical issues.

It is a good idea to reset the codes and perform a test drive to determine if the code is logged again.

If the oxygen sensor is in fact faulty, it should be replaced. The fuse running to bank 2 sensor 2 should also be checked and replaced if need be.

The wiring and connections between the sensor and the ECU should also be checked for damage or fraying. These should be fixed accordingly.

It is also important to ensure that the connections are properly fixed to the components.

Seriousness

Fault code P0158 should be considered a moderately serious problem. There is no immediate danger to the engine or its components but operating in this state can eventually cause damage.

It can also cause the vehicle to run very poorly after enough carbon buildup is caused. The fuel economy will also be very poor.

It should ideally be fixed as soon as possible.