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How to Fix P0135 Code: “O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)”

How to Fix P0135 Code

If you're searching for how to fix the P0135 code, confirm that the error code exists using an OBDII scanner. Once you confirm that your vehicle registered a P0135 code, only one common DIY is to test the oxygen sensor for any damage signs. If the oxygen sensor does not look great, you need to replace it to eliminate the P0135 code. However, if the code was not fixed, you must take your vehicle to a professional mechanic to perform manufacturer tests. 

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The oxygen sensor must operate within a certain temperature level, and it should reach this temperature within a fairly short time. If the oxygen sensor did not reach the optimum temperature within the designated time, your engine would trigger a check engine light associated with a P0135 code.

As a driver, you need to be aware of what needs to be done when dealing with a common error code like the P0135 code.

This article provides you with all the details you are looking for to understand the P0135 code. We highlight the primary causes along with the symptoms. We also provide you with a simple DIY to help you get rid of the P0135 code at home without needing a professional mechanic. Finally, we provide a rough estimate about how much it will cost you to get rid of that P0135 code. 

What is the P0135 code definition?

The P0135 code definition is “O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1).” If you didn't get what the P0135 code means, it is crucial to go back to the basics about how the oxygen sensor operates and the purpose of having a heater circuit around it.

We will cover this basic information along with some additional details in the following section to help you determine whether the P0135 code is serious or not. 

What does the P0135 code mean? 

Most vehicles have two different oxygen sensors. There's a heater circuit responsible for bringing the oxygen sensors' temperature up to operate faster than unheated sensors in every oxygen sensor. Usually, oxygen sensors are equipped with a heater circuit; it takes the sensor between 20 and 60 seconds to get started and reached the optimum temperature. 

Another important reason for having a heater circuit is keeping the oxygen sensor at the optimum temperature even when your vehicle is not running tire speeds or stays idle. 

The heater circuit's efficiency is crucial because the faster your oxygen sensor reaches the optimum temperature, the easier it is for your vehicle's engine to optimize the efficiency of the catalytic converters. 

When any of the heater circuits goes bad, the vehicle's ECM will trigger the P0135 code immediately to inform you that it's taking the oxygen sensor longer than usual to reach the optimum temperature, which might affect the vehicle's overall performance.

The P0135 code indicates that the heater circuit at bank one is the culprit. Bank one refers to the side of the engine, and #1 indicates it's related to cylinder one and #2 indicates it's related to the opposite side. 

What are the primary causes for the P0135 code?

Automotive experts collected old potential causes for triggering a P0135 code, and these causes are listed below:

  • Problems with the power control module
  • Issues with the engine coolant temperature sensor
  • Troubles with the fuse
  • Malfunction in the ground wiring
  • Issues with the connections
  • Problems with the pre-catalyst oxygen sensor 

How do I know if it’s the P0135 code? Symptoms of the P0135 code

When your vehicle registers a P0135 code, you will notice one of the following symptoms:

Keep in mind that these symptoms can be linked to multiple potential causes, which means that you cannot rely on these symptoms to say it's coming from a P0135 code. Thus, the best and most accurate way to confirm a P0135 code is by using an OBDII scanner and performing a quick scan. 

How to fix the P0135 code?

Although the P0135 code is linked to a very sensitive component, the oxygen sensor, it's not too scary to deal with this code because there are plenty of good DIYs to implement at home to resolve the issue.

Our team conducted an in-depth review of all available recommendations by automotive experts. Fixing the P0135 code at home without needing a professional mechanic is crucial to eliminate needing the mechanic as much as possible. This way, you can save a ton on labor costs.

Let's take a closer look below at some of the methods you can apply to fix the P0135 code:

  • Is it really a P0135 code? 

Before you move any step further, you need to make sure that the P0135 code exists in the 1st place. To do that, you need to use a certain tool called the OBDII scanner.

This scanner is a small device that you can connect to your vehicle's internal computer to scan all internal errors. Keep in mind that this tool will display inactive and current or active errors, which means that you must know what to look for on the screen.

If the screen displayed a P0135 code, then your problem is linked to the heater circuit of the oxygen sensor on bank one. Thus, you can go ahead and test the following DIYs to resolve the issue. 

  • Does the oxygen sensor work properly? 

The quickest and most common DIY to get rid of a P0135 code is to inspect the oxygen sensor on bank one. Again, bank one is located at the site of the first cylinder of your engine.

Since the P0135 code is linked to sensor #1, you should be looking to the oxygen sensor connected to the exhaust manifold, not the other one on the catalytic converter opposite site. If you had a hard time locating the sensor, you could always refer to your vehicle's owner’s manual to get better-detailed guidance. You can also find some YouTube tutorials or graphics on the Internet for similar vehicles to locate the oxygen sensor. 

Carefully disconnect the oxygen sensor from the catalytic converter and perform a visual inspection. As you're looking at the sensor, check for signs of damages on the sensor itself and the wire harness. You might also need to check the metal tab as it might get damaged over time of use. 

If you notice any damage to the oxygen sensor, your only solution is to replace it with a new one. Before installing the new oxygen sensor, it is recommended that you refer you to or manual to make sure that you purchased the right one. A good tip would be to compare the old one to the new one and make sure they're identical.

If the oxygen sensor was not the faulty components, you have to consult a professional mechanic. 

  • Will the P0135 code clear itself? 

No, any error code associated with a check engine light does not clear itself. That's why when you connect an OBDII scanner, you might see previous error codes that your vehicle suffered from, which were not cleared out.

If you could get rid of the P0135 code successfully, you could simply ask the OBDII scanner to delete any inactive error codes.

After deleting these codes, it is recommended that you scanned the vehicle one more time to make sure that the P0135 code was deleted completely and didn't occur again, which indicates that you were successfully able to get rid of the problem. 

  • What does the mechanic say? 

If you could not successfully get rid of the P0135 code, the only option for you is to take your vehicle to a professional mechanic. Usually, when an error code within your vehicle isn't resolved with comment DIY's, the mechanic performs certain manufacturer tests to dig deeper and find the main culprit.

These manufacturer tests usually differ depending on your brand or automaker. However, the overall approach and step-by-step are very similar and most larger brands. 

P0135 code diagnosis mistakes 

It's very important to highlight that many people might perform the wrong diagnosis when dealing with a P0135 code. For example, a good number of drivers might immediately attempt to replace the oxygen sensor when dealing with this code.

However, and as we indicated before, the problem might be linked to issues with the fuse or probably the wiring connections. Thus, it won't be anything but just a waste of time, effort, and money when replacing the oxygen sensor without digging into all possible culprits. 

That's why it's very crucial to perform a detailed inspection of your oxygen sensor before replacing it. For instance, if you didn't find any signs of damage, there is no need to replace the sensor, which gives you a clear sign that your problem is linked to a different component.

If you found it challenging to confirm whether the oxygen sensor looks good or not, it's recommended that you reach out to your professional mechanic and have a conversation with him about whether it's worth replacing the sensor or not. 

Can I drive my car with a P0135 code?

The good news is that a P0135 code is not super complicated and is not life-threatening. In other words, when you deal with this code, you don't have to run immediately to the repair shop and fix it.

However, if you delayed fixing a P0135 code for an extended time, complicated outcomes might happen, which might cost you thousands of dollars at a certain point. 

How much does it cost to resolve the P0135 code?

Expected repair costs for fixing a P0135 code differ significantly depending on the root of the problem. For example, if the issue comes from a bad oxygen sensor, repair costs can range from $200 to $300.

On the other hand, if your problem is as simple as a blown a fuse, repair costs can only be as low as $5!

However, if the issue is more complicated and associated with problems with the wiring, repair costs can get a little higher and reach a range of $100 to $1000 depending on the severity of the issues in the airing.

Keep in mind that all these repairs have a labor cost component, which means that the range might be slightly different if you go to a small repair shop versus when you go to a dealership. 


Temperature is a very critical component in operating most of your vehicle's internal components. The oxygen sensor needs to reach a certain temperature level for optimum performance, and this temperature must be reached within a short time. If the sensor failed to heat up by the designated time, your vehicle's internal computer would throw an error as associated with a P0135 code.

When dealing with this error, you are not dealing with a life-threatening situation, which means that you don't have to fix it immediately. However, our team provided you with a simple DIY to help you fix the P0135 code at home without needing a professional mechanic.

If your car has other major complications aside from the P0135 code, we always recommend that you think about the benefits of selling your car to Cash Cars Buyer. 

Cash Cars Buyer is one of the top-rated car removal companies in the nation that guarantees to pay you the top dollars and will provide you with free towing despite your living location around the United States. 

The best thing about Cash Cars Buyer is that our process is very straightforward and doesn't take more than a couple of days to get your vehicle removed safely and for the most money. 

To learn more about our process and our team, you can reach out to us by giving us a call at 866-924-4608 or visit our home page click on the free instant online offer.

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