Code P0135

Trouble Code P0135: How to Diagnose and Fix It?

Code P0135After 1980, every car was designed with a new sensor called the O2 sensor. And each car has at least one of these sensors. The main job of this device is to balance the power of the air-to-fuel ratio of the engine and keep it at an ideal rate so that it can balance the fuel economy with emissions. So this sensor mainly figures out how much oxygen is exhausted from the engine and compares it with the amount of air in the gasoline. Every car has an ECM system that mainly provides the condition of every system on the computer. When bank 1 of the O2 sensor faces any issue in measuring this amount, the ECM catches it immediately and prepares a trouble code known as P0135. If you face the same issue and want to get rid of it, then this article will help you a lot.

Quick Solutions:

  • If the sensor is faulty, replace it.
  • Inspect and repair any damaged wiring or connectors.
  • Locate and replace the blown fuse if necessary.
  • Have a professional check the ECM for faults.

The meaning of the trouble code P0135:

The meaning of the trouble code P0135 is issued with the heater circuit of the O2 sensor in bank 1, sensor 1. This generic code indicates to the engine control module that there is an issue with the heater circuit of the o2 sensor, then the car’s computer finds the issue and marks it as a trouble code, sending it to the vehicle’s dashboard. And if you’re already familiar with OBD codes, you’ll know that P-related codes are generated by the car’s powertrain control module or PCM. And this code issue is specifically located at the heater circuit of the O2 sensor in bank 1, sensor 1. This trouble code mainly causes problems with the car’s fuel economy and performance.


There are a few reasons behind this P0135 code. And if you want to fix this issue on your own, then you must need to know about this cause, and it’s listed below:

  • Damaged O2 sensor
  • Short or open circuit in the heart section,
  • defect in the catalytic converter,
  • Vacuum leakage,
  • issues in the engine air intake system,
  • Malfunction in engine coolant temperature sensor
  • Low fuel pressure


There are some basic symptoms you can find in your car for this trouble code P0135, and those are:

  • The blinking check engine light
  • less fuel consumption
  • Roughly, experience while driving the car
  • Bad smell from exhaust gas or emit black smoke.

The diagnosis process of the error code P0135:

If you are new with your car and want to solve this, then you must know how to find the issue in your car. Mechanics are also followed in every step, and I think if you know about this, you can easily point out the location of trouble:

  • Visually inspect the electrical wire and connection of the O2 sensor heater circuit bank1, sensor 1.
  • From the scanner, examine the freeze frame data and then clear it from the memory to ensure the code is still on the system or not.
  • Test all data from the O2 sensor and check if the heater is working or not.
  • Examine all of the O2 sensor’s connections.

If you don’t find the issue in the process, you can read the car manual to learn all about car parts. Some of the car manuals also come with solutions like that so that people can get help from there.

Before making any changes, there are a few things you need to know about this issue that can be made by you or any technician. The first one is to change any sensor or wire without confirming the issue. Many times, people think the issue is only created by the heating circuit and change it. For this reason, they don’t want to dig deep into the problem and just replace the old one.

But after all, they again found the same issue in the scanner. And the second one doesn’t check the covered area of the heater circuit. Most of the time, people forget about this and leave it. Another one is not changing the oil in the O2 sensor after using the car. The oil gets contaminated, and it also creates issues. The last one is not checking the replaced O2 sensor with a scanner. Always check the O2 sensor and the wire after doing any replacement or repair. Ensure the installation is perfect or not.

How to fix the P0135 trouble code?

To fix the issue of P0135, you need tools like a wire brush set, screwdriver, etc., so first collect them all and then start the process. And after reading the diagnosis process, I think now you can find where the problem is. The solving steps are:

  • First, scan the car engine system with a digital OBD scanner and find out if the code is there or not, then clear it from memory. After that, run the car for a test, and again test the car system to ensure the code is there or not. Sometimes if you forget to clear the memory, the code is stored there and shows you. So if you do this, you can ensure whether the issue is in the system or not. Most professional technicians test the previous and present results of the scanner just to be sure of any issue in the car.
  • Locate the O2 sensors on the car. Most of the time, you can find it near the exhaust manifold. Check if this sensor is working or not. If it’s not working, then replace the damaged one and install a new one. But if it’s working, then go to the next step.
  • Check if there is an open or short circuit in the heater circuit. If you come across one, repair it as soon as possible. Otherwise, replace it.
  • If you find any damaged fuses in the heater circuit, change them.

If you still can’t fix the issue with the car, you can get help from a technical bulletin site or your car. You can find every car’s details and solutions if this type of problem-solving is in there. But if you are still in the dark, then contact your mechanic. It will cost you some money, but save you time.

How serious is the P0135 OBD2 code?

The O2 sensor is mainly used to measure the oxygen level of the exhaust gas, and if anything happens in the heater circuit, it will start creating more heat in the car engine. With that, O2 sensors need extra time to measure their value. As a result, the engine faces issues like stalling, running inadequately, etc. That’s why you can feel uncomfortable while driving the car. This issue also increases fuel consumption and spreads the bad effects of fuel economy. And if this issue is not solved on time, it will start to make black smoke with a bad odor. These two things create pollution, but you can still drive your car with them. Try to solve the P0135 issue so you can get a smooth drive.

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