Key Takeaways

  • A P0136 code is an oxygen sensor code.
  • Usually, this means your oxygen sensor has gone bad.
  • There are two sensors per catalytic converter.
  • The sensor reacts to oxygen, creating a voltage, which it sends to the ECM.
  • Replacing the o2 sensor is a fairly straightforward process.

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Sometimes, a car will throw codes. And the codes mean you need to act. But what is a P0136 code and how do you fix it?

A P0136 code is an oxygen sensor code. This means your oxygen sensor has gone bad. To fix this code, you usually want to replace the sensor. Replacing the sensor is a very straightforward process. It involves unbolting the old one and bolting the new one in.

I’m a mechanic with five years experience diagnosing and repairing vehicles. I am ASE certified and received my degree in automotive repair. I receive training on the most recently released automotive technology and I diagnose and repair vehicles with the latest and most up-to-date tools and software.

Table of Contents

Oxygen Sensors

To understand your code, you first need to understand what an oxygen sensor is. The job of an oxygen sensor is to measure the amount of oxygen in the exhaust stream. There are usually two oxygen sensors per car. With V type engines, there are 4 sensors per car.

Another rule of thumb is that there are two sensors per catalytic converter. V type engines have two exhaust banks, therefore they potentially can have two catalytic converters. There are O2 sensors before the catalytic converter, and after the catalytic converter.

The chemical that the o2 sensor is coated in reacts chemically to oxygen present in the exhaust stream. When the sensor reacts it creates a voltage and sends that data to the engine control module. Then the engine control module takes this information, and then adjusts the amount of fuel it delivers to the engine.

A faulty oxygen sensor will cause a check engine light which will cause a diagnostic trouble code. And in this case, when you hook up a scan tool the ECM will tell you that the post catalytic converter oxygen sensor has a wiring issue. When this is the case, this means the oxygen after your catalytic converter has an issue.

What the issue is exactly is something we’ll go over later in this article.

How To Fix Toyota p0136

The first step you’re going to want to do is check that the oxygen sensor is operating correctly. Since the heated oxygen sensor informs the ECM, you can read the voltage of the o2 sensor with a scan tool. Hook up the scan tool and look for an o2 sensor reading.

A properly functioning oxygen sensor should be outputting between 0.1 and 1.0 v. If the exhaust system is operating properly and the oxygen sensor as well, this is what the readings should be. If the voltage is out of spec, move on.

The next thing you’re going to want to do is to check the o2 sensors wiring. Remember, it’s the oxygen sensor after the catalytic converter. So you may have to get underneath the car depending on how the engine bay is set up.

Make sure the wiring looks good and no wires are damaged or cut in any way. These wires are very thin and the protective layer around them can corrode. Check for any sign of this in the wiring.

Sometimes, there is an oxygen sensor fuse for the rear oxygen sensor bank. This fuse can pop, leaving you with the code you are experiencing. Check your vehicle’s owner’s manual for a fuse box diagram and locate the o2 sensor fuse.

Once you have located the fuse, pull the fuse out of its home and inspect it. If it looks burnt, replace the fuse, clear the codes, and see if the code comes back. If it doesn’t, you have fixed the problem.

Another thing you can check is the power supply going to the oxygen sensor. The oxygen sensor needs to be heated up in order to work at a correct operating temperature. So there is a heater circuit within the o2 sensor.

The job of this heater circuit is to get the o2 sensor up to operating temperature so it can start working correctly. The power supply to this circuit could be damaged. To test, take a multi meter out and test the voltage going to the circuit. If you don’t see voltage going to the circuit, trace the wire up and look for shorts.

Check the exhaust system for exhaust leaks. Exhaust leaks can cause the o2 sensor to give false readings since extra oxygen would be in the exhaust system. You can check for exhaust leaks by listening closely for loud engine sounds coming from the exhaust.

Lastly, check for other engine issues. Other issues like extra intake air volume, bad engine’s fuel injector pulse, high exhaust gas temperature, and more could be the cause of this code. Make sure your engine is in good working order if you have tried all the other repairs and they are not working.

Prevention Tips

To prevent this issue, regularly maintain your vehicles. Do your oil changes, your tire rotations, all the preventive measures you can think of. Doing this will help prevent codes like these since it will have your vehicle inspected by a mechanic on a regular basis.

Also, use the best fuel you can possibly use in order to prevent this code, as the gas used has a direct effect on erratic output voltages. Maintain proper tire pressure since tire pressure affects gas mileage and your air fuel ratio, and avoid driving aggressively. Driving aggressively can directly affect the stoichiometric air fuel level.

How To Replace An Oxygen Sensor

Replacing an oxygen sensor is really easy! All you need is a 22mm wrench or a special socket. Now, these items are usually really baked into the exhaust so it’s going to take some elbow grease and finesse to get them out.

You don’t want to wrench too hard on the o2 sensor since you can do damage, but you don’t want to be too light on it since you won’t be able to get it out. If you want, you can purchase an o2 sensor socket, which is a special socket that fits around an o2 sensor’s head.

This socket fits over the head of an o2 sensor perfectly and you can place a ratchet to the end of the socket. Once everything is in place, you just apply torque to the socket and the o2 sensor will come loose. Once the o2 sensor is out of the exhaust hole, you can remove the electrical connection.

Usually, to remove the electrical connection, you just press down on the connector and pull. This frees up the connector and allows you to totally remove the o2 sensor. To replace the o2 sensor, just place the sensor back into the o2 sensor hole, and screw it in.

Apply minimal torque since the item is electrical. You may also apply some grease if you wish. Hook up the electrical connection, clear the codes, start the car, and you should be finished.

So as you can see, replacing the o2 sensor is a really easy process that you can do at home. Just purchase the o2 sensor and replace it.

Different Types Of o2 Sensors

There are two main types of oxygen (O2) sensors used in cars: the zirconia sensor and the titania sensor. Both types work by measuring the oxygen content in the exhaust gas to provide feedback to the engine control module (ECM) about the air-fuel ratio.

  • Zirconia O2 Sensor: The zirconia sensor is the most commonly used type of O2 sensor in modern cars. It contains a ceramic element made of zirconium dioxide that generates a voltage signal based on the difference in oxygen concentration between the exhaust gas and the surrounding air. The voltage signal is then sent to the ECM, which adjusts the air-fuel mixture accordingly. Zirconia sensors are highly accurate and reliable but require a high temperature to operate.
  • Titania O2 Sensor: The titania sensor is a newer type of O2 sensor that uses a ceramic element made of titanium dioxide instead of zirconium dioxide. Titania sensors are less expensive and require a lower operating temperature than zirconia sensors, making them more suitable for some applications. However, they are less accurate than zirconia sensors and tend to deteriorate more quickly.

These are the two main types of o2 sensors found in modern day vehicles.

How To Fix Toyota P0136: Learn, Repair & Prevent

About The Author

Christopher Sparks

Christopher Sparks

Christopher Sparks has been servicing vehicles since 2012. After completing the automotive studies program at Camden County College, he was awarded an Associates's Degree in Applied Science. His first job was a lube-tech at Jiffy Lube, and is currently an independent B-Technician servicing vehicles for the United States Postal Service. Christopher is ASE certified and loves rebuilding engines.

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