P0135 code — how to fix error fast

If you used a scanner tool to read the code P0135 after issues with the disrupted engine performance and combustion, we know it can get frustrating on its own. However, the key thing you can do is try to get to the bottom of the P0135 code meaning and figure out how to remove it.

In this guide, we’ll help you do just that by going over the code meaning, potential causes, and steps to diagnose and fix it. We’ll also give you a few tips on how to make sure this code never happens again, so let’s get into it.

Why you can trust REREV’s OBD2 code advice: Our automotive expert researchers with experienced mechanics undertakes a thorough research methodology to deliver precise insights on OBD codes. Find out more about OBD2 codes research process..

What does code P0135 mean?

The problem code P0135 indicates a malfunction in the oxygen sensor circuit. Specifically, it refers to the Bank 1 Sensor 1 oxygen sensor, which is located in the exhaust system before the catalytic converter. The oxygen sensor detects the amount of oxygen in the exhaust gases and sends this information to the engine control unit (ECU) to adjust the air-fuel ratio for optimal combustion.

When the oxygen sensor circuit is malfunctioning, the ECU cannot accurately adjust the air-fuel ratio, which can lead to poor fuel economy, reduced engine performance, and increased emissions. Therefore, it’s important for drivers to fix this code as soon as possible to prevent further damage to the vehicle.

What causes the P0135 code?

Figuring out the cause of the code may not be that simple even though you now know why it occurs in a car. To help you on that path, we’ll list a few of the most frequent reasons behind the code showing up:

Faulty oxygen sensors

Over time, the oxygen sensor can become contaminated with oil, coolant, or other substances, which can cause it to malfunction. If it does, the air/fuel mixture can get all messy and the worst thing besides it triggering the code P0135 is that it could affect your engine’s operation.

Electrical and wiring issues

Damaged, corroded, or disconnected wiring can prevent the oxygen sensor from sending accurate signals to the ECU. In this case, the code may simply appear as the wiring affects the sensor to underperform, and fixing the wiring or electrical issues may lead to a solution.

Problems with the ECU

Sometimes, the code P0135 may even be caused by a faulty ECU that improperly reads the information it receives from a sensor that’s actually perfectly fine. Of course, ECU issues could lead to much more dangerous problems with the engine itself, but the code may be one of the first signs you need to deal with a faulty computer.

If the code P0135 appears in your car and is caused by a malfunction of the oxygen sensor, it may manifest through rough idling, reduced fuel efficiency, and the “check engine” light coming up on the board.

Which car models does the code P0135 affect the most?

The code P0135 may occur in any vehicle that has a system with an oxygen sensor placed before the catalytic converter within the exhaust system. Still, we pulled up some info to tell you about the cars that are more likely to show the code than others:

• Honda Civic: The Honda Civic is known for having issues with its oxygen sensors in general, and P0135 is a common problem.
• Toyota Corolla: The Corolla is another car that is prone to oxygen sensor issues that could lead to a code showing up.
• Mazda 3: Some Mazda3 models have been known to experience P0135 due to problems with the oxygen sensor or its wiring

It’s worth noting that these are just a few examples, and many other car models can also be affected by P0135.

How to diagnose the P0135 code?

Diagnosing the code requires some specialized tools and equipment, including a scan tool, a digital multimeter, and a propane enrichment tool. Here are the general steps to diagnose the code:

Use an OBD2 scanner to check the list of DTCs

The easiest way to diagnose the P0135 code is to use an OBD-II scanner, which can read the diagnostic trouble code and provide additional information about the issue. This can help pinpoint the specific component or system that is causing the error.

Use a multimeter to test the oxygen sensor

Since this code is related to the oxygen sensor, it’s important to inspect this component for any signs of damage or wear. This may involve removing the sensor from the engine and visually inspecting it, or using a multimeter to test its electrical resistance.

Check the wiring and connections

The heating circuit of the bank 1 sensor 1 oxygen sensor relies on proper wiring and connections to function correctly. Checking these components for damage or corrosion can help identify any issues that may be causing the P0135 code.

Check for any related codes

This code is just one of many diagnostic trouble codes that can be related to the oxygen sensor or emissions control system. Checking for other codes that may be present can provide additional insight into the root cause of the problem.

Without the proper diagnostic toolkit, you’ll have a hard time diagnosing the code and it’s best to leave this to a trusted mechanic. Still, if you feel your vehicle’s engine surging and losing power, it may point to a poor combustion mix accused of an inoperable oxygen sensor. So, that could be your first clue about the issue.

How to fix the P0135 code?

The appropriate fix for the P0135 code will depend on the underlying cause. Here are some potential fixes and cost estimates for each cause:

Replace the faulty oxygen sensor

If the oxygen sensor itself is faulty, it may need to be replaced. This involves removing the old sensor from the engine and installing a new one in its place. A new oxygen sensor may cost between $50 and $250 depending on the car’s model.

Fix the wiring and electrical connection issues

If there is an issue with the wiring or connections related to the heating circuit, mechanics may need to repair or replace these components. This may involve soldering damaged wires, replacing corroded connectors, or installing a new wiring harness.

Check the ECU for proper operation and repair if necessary

Sometimes the ECU failure can be the culprit behind the code and that means you’ll have to test the ECU and repair or replace it if necessary.

It’s also worth checking for a blown fuse since it could lead to problems with the code and a false alarm being submitted through the scanner tool. To deal with this issue, you may need to check for a blown fuse within the fuse box and if that’s the case, it’s one of the most affordable ways of fixing the code.

How to prevent the P0135 code?

Preventing the P0135 code is all about maintaining the oxygen sensor and related components. We wanted to give you an overview of the main maintenance routine aspects that reflect on the performance of the sensor, so here are some preventative measures to take:

• Follow the manufacturer’s recommended maintenance schedule for the vehicle.
• Change the engine oil and filter regularly to prevent contamination of the oxygen sensor.
• Avoid using leaded gasoline or fuel additives that can damage the oxygen sensor.
• Keep the exhaust system clean and free of debris to prevent damage to the oxygen sensor.

By following these preventative measures and properly maintaining the oxygen sensor circuit, drivers can avoid the hassle and expense of dealing with the code.

Our take

Overall, this guide has hopefully helped you realize how such a tiny issue like a malfunctioning sensor could lead to massive trouble with your car. So, it’s important to act right after you read code P0135 and get the oxygen sensor to work properly again.

With our pieces of advice and a helping hand from a trusted mechanic, we are confident you can figure out a solution to the issue.