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What Does Fault Code P0140 Mean? Symptoms, Causes, and Fixes

What Does Fault Code P0140 Mean? Symptoms, Causes, and Fixes

If you have an error code “P0140,” you might wonder, “what does fault code P0140 mean?” Typically, this error code means a problem with the post-catalytic monitoring oxygen sensor.

Auto Repairs Are EXPENSIVE


Your vehicle relies on many warning lights to grab your attention to internal problems. One of the most important warning lights you should pay attention to is the check engine light.

The check engine light illuminates for various reasons, and there are many potential causes for what's going on internally. You need to read the error code associated with the check engine light to determine the root culprit causing the issue.

One of the very common error codes you might encounter during your vehicle's lifetime is fault code P0140. You must understand what this code means and what it entails because you will get a good understanding of what negative consequences to expect if you ignore the problem.

In this article, we will walk you through all the details you need to know to understand what fault code P0140 means? In addition, we will highlight potential repair options and associated repair costs to prepare you to deal with this code.


How To Fix P000A Code

What does fault code P0140 mean?

When your check engine light reveals a fault code of P0140, you have a problem with a post-catalytic to commit monitoring oxygen sensor. This sensor is responsible for measuring how much oxygen leaves in the exhaust after the exhaust passes through the catalytic converter.

This information is very important, and if your internal computer does not receive the right amount of oxygen associated with the exhaust comma, it will not understand the catalytic converter's performance. In other words, your computer might assume that the catalytic converter is not working properly and will complain that you don't have a working catalytic converter.

In that case, you can easily not pass the emission test if you plan to do so. Therefore, whenever you deal with this fault code P0140, you must take it seriously and consult your mechanic to see how you can fix or replace that oxygen sensor.

What causes the P0140 Fault code?

While the post catalytic monitoring oxygen sensor is expected to have an into its lifetime, sometimes you might deal with certain external factors that will force this sensor to fail prematurely.

Understanding these factors and these causes is very important because if you know them, you will eliminate them or at least avoid them from happening so you can enjoy the longest lifetime of this sensor possible.

Let's take a closer look at what automotive experts suggested as the main causes of the P0140 fault code:

1.    Your vehicle ECM cannot detect the oxygen sensor activity

The first and most common cause of triggering the P0140 fault code is when your vehicle's ACM does not detect any activity from the oxygen sensor. As we mentioned earlier, this sensor should continuously communicate with your vehicle's ECM and let it know how much oxygen is available in the vehicle's exhaust.

If the computer does not receive this information, it will immediately assume that the sensor is not working properly, which means that you need to check it and replace it if necessary. The ECM will immediately ask your computer to trigger a check engine light.

2.    No voltage in the oxygen sensor

The second potential cause for triggering the P0140 code is when your internal computer detects that there is no voltage in your oxygen sensor. If the computer feels that there's no voltage, it will immediately assume that the sensor is broken and needs replacement. As a result, it will trigger the check engine light to grab your attention so you can look at it and fix it.

3.    Your vehicle's ECM misinterprets the oxygen sensor or the mass air flow sensor

Sometimes your vehicle's computer might not receive the right information from the oxygen sensor. In other words, it cannot translate the information sent by this sensor in the form it's used to hear or receive. In that case, it will immediately trigger a check engine light.

4.    The ECM oxygen sensor circuit is malfunctioning

Finally, suppose the ECM oxygen sensor circuit has a problem. In that case, it will appear to the vehicle's computer that the oxygen sensor itself is not working, and it will assume that it needs replacement. However, when you deal with a fault code P0140, you must ask yourself what fault code easy 140 means? Because this will help you understand that it is not immediately something directly related to that sensor itself. It could be an issue with the circuit you must check and fix.

That's why you don't need to immediately assume that the sensor is bad, and you go ahead and replace it. Instead, you need to step back and discuss with your mechanic what needs to be done to fix the issue.

How long does it take for the check engine light to come back on after reset

How much do you expect for fixing fault code P0140?

Luckily, fixing a fault code P0140 is not very expensive. However, sometimes performing the diagnostic for the check engine light might be a little bit more expensive. Otherwise, your mechanic might charge you $114 to perform a diagnostic to see what's going on with the check engine light.

Once your mechanic confirms it's a fault code P0140, he will recommend replacing the sensor. Typically, dealing with this sensor does not cost you more than $20 for most manufacturers, including Ford, Toyota, BMW, and others.

Symptoms of error code P0140

As you mentioned, you cannot immediately know what type of errors you're dealing with when your vehicle has a check engine light. That's why, if you are considering learning more about the fault code P0140, we highly encourage you to understand what other symptoms you will encounter as this error code is triggered.

Let's take a closer look at some of the symptoms of error code P0140:

1.    A check engine light illuminating

Of course, when an error is associated with your engine, you will immediately see the light illuminating the check engine. But, as we always say, you must always take the check engine light seriously because it could be linked to a significant internal problem.

Therefore, once you notice the check engine light, you have to use a scanner that translates the check engine light into forms of error code so you can translate. So once you see that the scanner is telling you it's a P0140, you know what you're dealing with and what to do next.

2.    Your vehicle is running Rough

The other thing you might encounter when dealing with a fault code P0140 is your vehicle is running very rough. A vehicle running rough could be associated with many other problems, and that's why you cannot immediately assume it's a P0140 error code when you're dealing with this issue. Instead, you must perform a thorough inspection with your mechanic to know what exactly is going on.

3.    Vehicle hesitation

You will notice that your car is not producing the good energy it should. As a result, there will be some lag and hesitation every time you try to get your vehicle going. Remember that this is another common problem linked to multiple problems. That's why you need to talk to your mechanic about what else could be causing the vehicle hesitation and whether it's associated with a P0140 error code or not.

4.    Issues with the air-fuel mixture

Finally, when you wait for the error code P0140, you'll notice that your vehicle's computer cannot keep up with the right ratio between air and fuel. As you might already know, your engine must receive a specific amount of air and fuel and then make it together to generate the required energy. So if there's any problem with the ratio between the two, you can easily deal with problems, and you'll feel that your vehicle is not generating what you're looking for.

Once you deal with this situation, consider checking that check engine lights and look closely to see if it's an error code P0140 or not.

Check Engine light

Is fault code P0140 very serious?

By now, you should understand what could cause the fault code P0140 and what exactly it means. It's very important to understand whether this problem is critical because you will then decide on how long you can wait and whether you must fix it immediately or not.

Since this sensor has to do with how much air and fuel goes inside the engine, it is critical and serious. You must immediately have your mechanic resolve that issue so you don't deal with further complications that could cost you thousands of dollars, especially if things got more damaged in the engine itself.

You don't want to get to a point where you cannot drive your vehicle properly, and your vehicle is acting up so that you cannot control it, so you stop it or slow it down during traffic or when you're driving on the highway.

Is it a good idea to fix fault code P0140 by myself?

As we always say, when dealing with any problems associated with the engine, it is better to leave it to professionals, especially if you change a small sensor inside a very sensitive component.

However, even if you don't have the right mechanical skill sets, you can always get a scanning tool that allows you to at least narrow down the potential list of problems that you're dealing with. In other words, you can invest in a cheap OBDII scanner and then connect it to your vehicle's computer to try scanning any error codes.

This is a very important step and will save you a lot of time and effort with your mechanic. Once you tell your mechanic that you're dealing with a fault code P0140, then it's a matter of replacing that small component which is going to cost you only $20 or so.

Therefore, if you think about it and if you think about the amount of money you're going to save by doing it yourself, it's worth leaving it to professionals rather than introducing mistakes that could cost you lots of money since you're dealing with the engine.

Of course, if you're a mechanic or have previous mechanical experience and feel comfortable fixing this sensory, you can go ahead and do so. However, it will have its risks, and considering that it's not a very expensive repair, we still recommend that you have a professional do the job for you.

Checking Your Engine Oil

Final thoughts

You will deal with lots of issues with your vehicle during its lifetime. You will see lots of warning lights on the dashboard, and that can be a little bit scary to experience drivers.

However, learning about one or two warning lights helps you protect what to do next and makes you feel scared about dealing with your vehicle's problems.

One of the most common questions that we received from our readers is what does fault code P0140 mean?

This article highlighted all you need to know about this error code and listed the potential causes and symptoms you might experience when dealing with this error code. In short, this error code indicates that you're having a problem with your vehicle's post catalytic oxygen sensor.

Once you figure out this problem, you must immediately replace the sensor for your vehicle to operate properly. However, if your vehicle has many other problems and costs are closer to 75% or more than your vehicle's value, you want to step back and evaluate whether you should sell this vehicle instead.

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