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The Check Engine Light can come on for almost any reason related to the engine, drivetrain, emissions, etc. When you identify that your ECU is displaying the error code P0136, it means that there is an issue with your vehicle’s catalytic converter or the oxygen sensor that's located right after it.
Thankfully, there's no need to worry because JEGS can help. Read on to learn more about what P0136 is, how to fix it, and what might be causing it.
What Is a P0136 Code?
The P0136 code is an error code displayed as a Check Engine Light on your dashboard. This code is triggered by an O2 sensor circuit malfunction, which can be caused by wiring problems, damage to the sensor, or an exhaust leak. The code specifically refers to an issue with the engine's second O2 sensor in Bank 1. Bank 1 of the engine is where the first piston is located.
There are two banks in V-shaped engines, Bank 1 and Bank 2. Bank 1 is on the side of the V where the first piston is located, and Bank 2 is on the side of the V where the last piston is located. When it comes to in-line engines, like an in-line six or in-line four, you don't have to worry about this because there is only one bank.
As for the sensor, the P0136 code refers to the second oxygen sensor in the circuit. The first sensor is located before the catalytic converter, so the second sensor is located after it. Vehicles need a catalytic converter to measure the oxygen and other byproducts of combustion to ensure that the engine operates within emissions laws – this helps the ECU adjust how much fuel is dumped in the cylinders by determining if the exhaust mixture is too lean or rich.
When the sensor has a reading outside .1 or .9 volts (usually too low) for longer than two minutes, it will trigger the code. P0136 can also be triggered if the sensor is not communicating with the ECU due to loss of power.
What Are the Symptoms And Causes of a P0136 Code?
The Check Engine Light is the first symptom you'll notice when you have a P0136 code. Typically, this will be the only symptom people see because it doesn't damage the vehicle or cause it to enter limp mode. Instead, you’re more likely to notice the symptoms over time.
For example, you might have worse fuel mileage because your engine’s air-to-fuel ratio is slightly off. Another common symptom you may have is a slight decline in performance. However, if your catalytic converter is completely blown out, you may notice a slight gain in horsepower. While that might be more fun and make your car sound louder, it's a sign that you must replace the part or fail your next emissions test.
When it comes to the causes, there are a few things you need to keep an eye on. First and foremost, a bad oxygen sensor is the most likely culprit. Whether it's an issue with the sensor being outside the .1 to .9 voltage range or the wires being melted, sensor damage is the most likely cause of a code P0136. That said, it's not the only possible cause. You may have an exhaust leak or a damaged catalytic converter if your engine displays a P0136.
It's also important to note that an engine’s computer can malfunction and trigger a P0136 code. While it's possible, it's rare and unlikely but more common in vehicles that have been flooded with salt water.
How Serious Is a P0136 Code?
You should always be worried when your vehicle displays the Check Engine Light; it's rarely a good sign. Some codes are more dangerous than others, and the P0136 code usually doesn't cause serious damage. Still, it can cause your engine an issue with its air-to-fuel ratio, resulting in misfires and damage to fast-moving parts in the cylinders like the pistons, piston rings, and even the crankshaft.
Another reason the P0136 code is serious is that you will fail an emissions inspection, mainly if the code was triggered because of damage to your catalytic converter. Therefore, you shouldn't drive with this code until you know the problem. Plus, driving with a failed inspection can result in hefty fines. Overall, it won't blow up your vehicle, but it's not good to drive around with the Check Engine Light, regardless of the code.
How Easy Is It to Diagnose a P0136 Code?
Engine codes are easy to diagnose once you know what code you’re dealing with, which is easier said than done. That's because you won't be able to identify the error code until you use an OBD-II scanner or engine tuner. These tools connect to your engine’s computer to read error codes, check the engine’s diagnostics, and much more. The port to connect the tool is usually under the steering wheel, and if you don't have a code reader, make sure you work with a professional instead of guessing.
Once you know you're dealing with a P0136 code, it's time to start your inspection. First, look over the sensor to see if it sustained any damage. You can check for physical problems by looking at the sensor and test for electrical problems with a multimeter to see if it's getting any juice. Consider the wires if the sensor looks okay but doesn't have power. Look at any wires going to the sensor or around the sensor to see if they have any damage. If the wires are frayed, broken, or melted, there's a good chance that you'll have to replace them.
Electrical problems aside, you can move on to inspecting other components. Because the sensor associated with the P0136 code is located after the catalytic converter, you'll want to inspect this component first. If there is any damage to the converter, it will have to be replaced to fix this code. You should also check the rest of the exhaust for leaks to ensure everything works properly.
When your Check Engine Light turns on, make sure you’re prepared. JEGS can help you prepare for a P0136 code because we carry many OBD-II scanners, exhaust parts, and sensor and wire replacements.
