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.
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). 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.
Honda describes the P0158 code this way:
The secondary heated oxygen sensor (HO2S) (sensor 2) detects the oxygen content in the exhaust gas downstream of the three-way catalytic converter (TWC) during stoichiometric air/fuel ratio feedback control based on the air/fuel ratio (A/F) sensor (sensor 1) output voltage. The secondary HO2S controls the air/fuel ratio from the A/F sensor output voltage to optimize TWC efficiency.
After current is applied to the secondary HO2S heater, if the secondary HO2S output continues to exceed the upper limit used during feedback control, a malfunction is detected and a DTC is stored.
Notice the O2 sensor patterns in the following image. When the O2 sensor behind the catalytic converter (the ½ downstream sensor) mirrors the pattern of the front (1/1 upstream) sensor, the ECM/PCM flags a code for catalyst efficiency. The catalyst on this vehicle has been gutted on both banks.
The following pattern is the proper pattern after the catalysts were replaced. But in order to detect catalyst issues, the rear sensor must be dependable. That’s what this protocol is about.
For additional technical information that can help you fix P0158, you can read our discussion about how the downstream oxygen sensor can trigger trouble codes.
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:
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.
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:
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.
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.
It’s best to delay your next trip if your scan tool retrieved a P0158 code. Otherwise, you might have to deal with various issues that can make driving a hassle and require costly repairs down the line. Once you confirm which oxygen sensor is faulty, you can shop for a replacement at CarParts.com immediately.
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