What Codes Will This Page Cover?
- P0157 O2 Sensor Circuit Low Voltage
- P0158 O2 Sensor Circuit High Voltage
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What Is the P0157 Code?
Symptoms
Causes
Seriousness
Can I Still Drive?
Diagnose
Difficulty of Inspecting
Get Additional Help
The P0157 and P0158 diagnostic codes are tied together and indicate two problems on opposite ends of a spectrum. These diagnostic codes relate to the catalytic converter, which converts gasses and pollutants in the exhaust into less-toxic exhaust fumes. These oxygen sensor circuits measure the air-fuel ratio coming out of the catalytic converter, and if it’s too low or high, you’ll receive one of these diagnostic codes.
More About Diagnostic Codes P0157 and P0158
O2 sensors will typically gravitate toward a low voltage reading if they’re failing. This is one of the reasons there are two O2 sensors: the secondary O2 reading should be a gentle up-and-down graph like rolling hills, validating the primary O2 sensor, which will typically be sharp peaks and valleys. However, if the voltage is especially low and stays that way for more than about 20 seconds, then you’ll receive diagnostic code P0157; if the voltage is especially high and stays that way for more than about ten seconds, then you’ll receive diagnostic code P0158.
What Are the Symptoms of a P0157 Code?
The symptoms of the code will typically depend on whether you’re receiving the code for low or high voltage. In some cases, regardless of the code you’re receiving, you’ll end up with no adverse conditions aside from the check engine light turning on. In other cases, however, you might end up with an exhaust odor, issues running your vehicle overall, a lower fuel economy, and roughness in the idling phase. All of these can indicate problems with this oxygen sensor.
What Are Some Causes of a P0157 Code?
The most common cause of these codes is actually a faulty O2 sensor rather than a serious problem within the mechanics. This is especially true if you’re only receiving one of these diagnostic codes, and there are no other codes firing to indicate that there’s a serious problem within the engine. However, you may also receive these diagnostic codes due to corroded or physically damaged wiring, battery voltage problems, issues with the fuel pressure being too high or low, and exhaust leaks.
How Serious Is the P0157 Code?
These diagnostic codes can be incredibly serious if the oxygen is actually off. It’s impossible to know whether the diagnostic code is coming up because the sensor is faulty or because the mechanics are broken, which is why it’s so important to talk to an expert before you start trying to decide what your next move is. A replacement sensor generally will be less serious than an exhaust leak, while issues with your overall voltage can cause other diagnostic codes to show up as well.
Can I Still Drive with a P0157 Code?
Much of the time, you can drive at least long enough to get your car to a repair shop. However, especially if the problem is actually an issue with the air-fuel ratio coming out of your catalytic converter, driving for extended periods of time with these diagnostic codes firing can result in serious damage to your engine. It’s best not to risk this and instead to talk to an expert as soon as you can.
How Easy Is It to Diagnose a P0157 Code?
The diagnosis process of these two codes can be fairly simple, especially if the problem is not inside the engine itself. Because it’s most common for you to see these diagnostic codes when there’s simply a faulty sensor, an expert may be able to inspect the electrical connections, note visible damage, and replace the oxygen sensor. However, this isn’t where the problem will always end, and if there are any other issues, it can become especially difficult. It’s best to leave the diagnosis up to an expert.
How Difficult Is It to Inspect a P0157 Code?
The inspection process, as with the diagnosis process, depends on the actual problem. If the problem is clearly-visible issues with the oxygen sensor 2, it may be something that you can easily pinpoint on your own. However, if it’s any deeper than that, you’re unlikely to be able to figure it out on your own. An expert can help you decide whether this problem is serious or just a surface-level issue.
Need Additional Help with Your P0157 Code?
If you want to make sure that you know what’s going on with your car and you’re able to fix the problem, then it’s important that you get an expert’s help when it comes to these diagnostic codes. An expert will be your best bet to help you solve these problems.
If you’re looking to find repair shops near you, then look no further than Kelley. This is the perfect way for you to find a local expert who can help you determine what’s happening with your car and what you can do to fix it.
If you need more information on diagnostic codes, then KBB has an entire database of OBD-II codes that you can use to learn more about different codes and find information about any codes your engine is throwing.
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