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P0135 OBD-II O2 Sensor Heater Circuit Bank 1 Sensor 1 Trouble Code




The P0135 code is an OBD-II trouble code that stands for 02 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1) which indicates that there is an issue with the O2 sensor heating circuit on bank 1 for the first sensor.

It is essential to use an OBD-II scanner to obtain trouble codes and then check the identified parts.

In this article, I will be talking about the P0135 trouble code, its symptoms, causes, and how to fix it.

What Does The P0135 Code Mean?

P0135 OBD-II O2 Sensor Heater Circuit Bank 1 Sensor 1 Trouble Code

The generic code P0135 means that there is a problem with the oxygen sensor heating circuit on bank 1. This code is set when the powertrain control module (PCM) recognizes that the oxygen sensor’s voltage signal falls outside the expected range.

The oxygen sensor, often known as an “O2 sensor,” is a vital engine management system component that measures the amount of oxygen in the exhaust stream.

The sensor transmits a voltage signal to the powertrain control module (PCM), which adjusts the fuel mixture to maintain maximum engine performance and reduce emissions.

Typically, the P0135 code indicates a problem with the oxygen sensor heating circuit.

The sensor’s heater element is used to quickly get the sensor to its working temperature so that it can accurately measure the amount of oxygen in the exhaust gases.

If the heater circuit isn’t working right, the sensor might take too long to warm up, or it might never get to the right temperature to work, which would lead to wrong readings and poor engine performance.

(Related: P0140 OBD-II O2 Sensor Circuit No Activity Detected Bank 1 Sensor 2 Trouble Code)

Which Models Are Affected By The P0135 Code

MakeAffected By P0135 Code

What Are The Possible Causes of the P0135 Code?

The P0135 trouble code is caused when the heating circuit on the O2 sensor malfunctions and the vehicle’s computer detects it.

The P0135 trouble code does not always mean that your front oxygen sensor needs to be changed.

It can also be caused by other factors.

The following are the most likely causes of the P0135 trouble code:

  • Defective oxygen sensor.
  • Defective connectors or wiring on the oxygen sensor of the engine.
  • The catalytic converter is damaged.
  • Vacuum leak on the oxygen sensor of the engine.
  • The engine coolant sensor is damaged.
  • Issues with the power control module (PCM)
  • A short circuit has occurred in the wiring.

(Related: O2 Sensors In Cars: Everything You Need To Know)

What Are The Common Symptoms of The P0135 Code?

With a P0135 trouble code, the check engine light is often the only sign because your car can still run with a faulty oxygen sensor heating circuit.

However, there are some other symptoms, such as:

  • Poor fuel economy
  • Warming up the engine takes a long time.
  • Excessive fuel consumption
  • Rough idle on start

If you notice any of these signs, you need to get your car checked out and fixed as soon as possible to prevent further damage to the engine or emissions system.

(Related: P0138 OBD-II O2 Sensor Circuit High Voltage Bank 1 Sensor 2 Trouble Code)

Is It Safe To Drive With a P0135 Code?

Yes, it is safe to drive with a P0135 trouble code. The P0135 trouble code is not a serious issue.

You can drive your car and do not need to make immediate repairs. However, as it can lead to poor fuel economy and higher emission levels, it is best to address the problem in a timely manner.

How To Diagnose The P0135 Code

If you want to easily diagnose the P0135 trouble code, you need to follow the steps below:

  1. To find the code, use an OBD-II scanner.
  2. Keep a record of all stored fault codes as well as any available freeze frame data. This information could be very useful if an intermittent fault is later discovered.
  3. Check the O2 sensor voltage with a multimeter. Locate the harness connector for the Bank 1 sensor 1 O2 sensor in your vehicle’s owner’s manual. For this step, follow the instructions written in the manufacturer’s manual. Inspect the fuse associated with that circuit if no power is getting to the O2 sensor.
  4. Examine the wirings and connections that are connected to the faulty sensor visually. Locate, color-code, function, and routing of all wires in the circuit using the manufacturer’s manual, and inspect for broken, damaged, burnt, or shorted connectors and wiring.
  5. If none of the above steps revealed a problem, it is almost certainly a problem with your bank. a single sensor 1 O2 Inspect and replace your O2 sensor.

(Related: P0131 OBD-II O2 Sensor Circuit Low Voltage Bank 1 Sensor 1 Trouble Code)

Most Common Mistakes When Diagnosing The P0135 Code

Here are the most common mistakes when diagnosing the P0135 trouble code:

  • Early replacement of the 02 sensors without inspection of other components.
  • Changing the oxygen sensor without fully examining the system for exhaust leaks and vacuum leaks.
  • Not scanning of the new oxygen sensor for the heating circuit to operate well.
  • Not checking the oxygen sensor wire harness for evidence of water intrusion into the harness cover.
  • Not checking for oil or other impurities on the oxygen sensor.
  • An improper PCM diagnosis.
  • The Change of any parts before performing a full visual inspection and testing all wiring with a multimeter.

(Related: P2195 OBD-II O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 1 Trouble Code)

How Much Does It Cost To Repair P0135 Code

MakeP0135 CodeRepair Cost
ToyotaYes$133 – $180
NissanYes$133 – $180
ChevroletYes$133 – $180
BMWYes$133 – $180
AudiYes$133 – $180
BuickYes$133 – $180
MercedesYes$133 – $180
GMCYes$133 – $180
SuzukiYes$133 – $180
TataYes$133 – $180
LexusYes$133 – $180
MazdaYes$133 – $180
MitsubishiYes$133 – $180
KiaYes$133 – $180
JeepYes$133 – $180
FiatYes$133 – $180
HondaYes$133 – $180
HyundaiYes$133 – $180
OpelYes$133 – $180
FordYes$133 – $180
FiatYes$133 – $180
PeugeotYes$133 – $180

What Repairs Can Fix The P0135 Code?

Repairs that can fix the P0135 trouble code include the following:

  • Repairing or replacing the malfunctioning oxygen sensor.
  • Repairing vacuum leaks.
  • Fixing or replacing the oxygen sensor’s damaged or corroded wiring.
  • Repairing exhaust leaks.
  • Replacing or repairing the oxygen sensor connection.
  • Changing out the blown fuse in the heater circuit.
  • Replacing or repairing the bank’s faulty heater circuit There is one sensor and one O2 sensor.
  • Reprograming or replacing the powertrain control module (PCM)

(Related: How To Clean O2 Sensor Without Removing It)

How To Fix The P0135 Code

To fix the P0135 trouble code, you need to:

  • Clean or replace the oxygen sensor if it is faulty, corroded, or covered in dirt or oil.
  • Repair or replace the wiring to the 02 sensors if it is frayed, damaged, or corroded.
  • Replace the fuse with the heater circuit after the short is corrected.

In Conclusion

Rough idle at startup and the check engine light aren’t a guarantee of an O2 sensor heater circuit malfunction, but it’s the most likely explanation in our experience.

When your check engine light illuminates, connect your OBD-II scanner to check for code P0135.

If you’re not into DIY, take it to your local shop and have it checked out. Trained mechanics are great at finding small problems with wiring and connectors that most DIYers miss.

A skilled mechanic can help you save time and money by resolving your problem the first time.



Vide Polowenski, Senior Mechanic

The information in this article is current and up-to-date in accordance with the latest mechanic SOPs.

Please take the time to leave a comment if this article has helped you in any way, you need additional help, or you have a suggestion.

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