The oxygen sensor, or the O2 sensor, is a device that monitors oxygen levels in your engine. This component gauges the air-fuel mixture by telling your vehicle’s computer, called the powertrain control module or PCM, if your engine is burning rich or lean.
The P0158 code indicates that the PCM has detected that the voltage signal coming from your O2 sensor remains above the normal range for a prolonged amount of time. Find out more about this code and what causes it with this informative guide.
What Does the P0158 Code Mean?
Diagnostic Trouble Code (DTC) P0158 stands for O2 Sensor Circuit High Voltage (Bank 2, Sensor 2).
The O2 sensor 2 is the downstream O2 sensor and it measures the amount of oxygen in the exhaust gases leaving the catalytic converter (cat). The O2 sensor sends the data it has gathered to the PCM in the form of a voltage signal. The PCM then monitors the operational efficiency of the cat and determines if it’s working properly.
The downstream O2 sensor is supposed to produce a steady voltage of approximately 0.45V. If the voltage coming from the O2 sensor is above approximately 0.45V, the air-fuel mixture is lean or lacks oxygen. Alternatively, if the voltage signal coming from the O2 sensor is lower than 0.45V, then the air-fuel mixture is running rich or has too much oxygen.
The OBD code P0158 is set when the O2 sensor 2 has been emitting a voltage signal above its normal range for a certain amount of time. The time that it takes to set this trouble code depends on different vehicle makes and models.
Note: The definition of code P0158 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.
What are the Possible Causes of the P0158 Code?
Like most OBD-II codes, there are quite a number of reasons why the P0158 code registers in your vehicle’s memory. Below are just some of the possible causes of P0158:
- Faulty oxygen sensor
- Faulty oxygen sensor heater circuit
- A rich running condition
- Faulty sensor wiring and/or circuit problem
- PCM software needs updating
- Faulty PCM
What are the Common Symptoms of the P0158 Code?
If you encounter the OBD code P0158, you might notice a few signs. If you experience any combination of the following symptoms, it’s a good practice to plug in your diagnostic tool to verify that the issue you’re dealing with is, in fact, the P0158 code.
- Illuminated check engine light
- Engine runs rich
- Lower fuel economy
- Rough idling
- Strong fumes
How to Diagnose the P0158 Code
Proper diagnosis of the P0158 is essential as it has quite a list of possible causes. The exact issue that triggered this OBD code needs to be addressed in order for you to reach an appropriate repair plan.
Diagnosis can be quite a challenge, but there are several resources and repair guides you could look into if you plan on doing the repairs yourself. Below is a video resource that can give you more information on the P0158 code:
How to Fix the P0158 Code
Repair steps for the P0158 code will vary depending on the vehicle’s year, make, and model. This is why there is no one-size-fits-all solution for this code. As stated above, proper diagnosis is very important.
If you’re unsure about how to go about fixing this trouble code, you can go to your trusted mechanic so that they can help you with repairs. If you plan on fixing the issue yourself, investing in informative and detailed repair guides is a good option.
Other Notes About P0158
It’s relatively safe to drive your vehicle for a short period of time if the P0158 code registers in your vehicle’s memory. However, if you continue to neglect this issue, your vehicle’s catalytic converter might get damaged. Once it does, you risk failing your emissions test.