A Toyota with a P0136 OBDII error code points to a problem with an oxygen sensor located in the exhaust system is having an issue.
There are two oxygen sensors called the upstream (sensor-1) and the downstream sensor (sensor-2).
What is a Toyota P0136 OBDII Error Code?
A Toyota P0136 is an “O2 Sensor Circuit Malfunction (Bank 1, Sensor 2)“.
Bank-1 is always the side of the engine with the number 1-cylinder.
Sensor-2 is the second oxygen sensor down on the exhaust, also called the downstream sensor.
It is called downstream since it is located after the catalytic converter.
Possible Causes of a Toyota P0136 OBDII Error Code
- Bad O2 Sensor
- Wiring (Open/Short)
- Faulty Computer (ECM/PCM)
The main cause of a Toyota P0136 error code is a faulty downstream oxygen sensor.
Faulty wiring such as an open or short can cause the same issue.
A faulty onboard computer (ECM/PCM) can also cause problems, but this is rare.
How To Fix a Toyota P0136 OBDII Error Code
Locate the downstream O2 sensor on the Toyota and examine the wiring.
The wiring can be tested for the correct voltages or for an open or short.
The harness can also be checked to be sure it is making a good connection.
A short in the wiring can cause low voltage on the O2 sensor.
After the wiring has been checked, the downstream O2 sensor can be tested or replaced.
Replacing the downstream O2 sensor is the most common fix for a Toyota with a P0136 engine error code
The sensor will be held on with two bolts which in some cases are difficult to remove.
The combination of corrosion and heat often makes the bolts hard to remove but right the right wrench; it can be done.
Summary
A Toyota with a P0136 code is usually a bad O2 sensor or wiring.
The sensor is located on the exhaust of the vehicle after the catalytic converter.
The wiring and harness should be checked and tested to see if there is an open or short a this would also cause the problem.
Usually, replacing the downstream O2 sensor solves the issue.
Sometimes the sensor can be difficult to remove since the exhaust heat can corrode the bolts.
If the bolts are very rusted and corroded, there are several techniques for getting such a sensor off a vehicle.
Have you had issues with a Toyota P0136 code? Let us know your thoughts below.