Diagnostic Trouble Code P0136

P0136 “O2 Sensor Circuit Malfunction (Bank 1, Sensor 2)”


What is code P0136?

Code P0136 stands for “O2 Sensor Circuit Malfunction (Bank 1, Sensor 2)”. This diagnostic trouble code can show up for a number of problems related to the post-catalyst oxygen sensor. Therefore, it is important to have a qualified technician diagnose the specific problem that caused the code to be stored in your vehicle’s computer.

Get this checked out soon by a CarAdvise shop, where the work will be guaranteed, and one of our expert techs will review any repair orders.

What does code P0136 mean?

A code P0136 is a diagnostic code that tells a technician that there is a problem with the oxygen sensor mounted in the exhaust system downstream of the catalytic converter. The ECM (Engine Control Module) has detected the problem and turned on the check engine light.

Even when finely tuned, the engine in your vehicle produces emissions of certain harmful gases. For this reason, the federal government has mandated that automotive manufacturers place a device called a catalytic converter in the exhaust stream.

The catalytic converter helps to filter out and convert these emissions into less harmful substances before they exit the tailpipe. The catalytic converter is also called a “catalyst” because it contains a ceramic matrix or honeycomb filled with platinum, palladium, and rhodium. These metallic chemical elements serve as catalysts for chemical reactions to the exhaust gases that pass through. The result is that harmful CO, HC, and NOx are changed into more benign CO2, H2O, and Nitrogen.

To confirm the effectiveness and efficiency of the catalytic converters, an oxygen sensor is placed after the converter in the exhaust stream. If the ECM detects that this oxygen sensor is not functioning properly, it might set code P0136 and turn on the check engine light.

What causes code P0136?

A number of causes can trigger a code P0136. That is why an accurate diagnosis is essential. Causes of this code include anything that prevents the ECM from receiving proper voltage from the oxygen sensor. For instance:

Most likely

  • Faulty oxygen sensor ($200-$500)
  • Damaged or deteriorated wiring to the oxygen sensor

Other possibilities

  • Corrosion on the oxygen sensor connector or ECM connector
  • Malfunctioning ECM

What symptoms are associated with this code?

Common signs associated with a code P0136 include the following:

  • The check engine light is on or flashing
  • Reduced fuel economy due to excess fuel consumption
  • Engine runs roughly, hesitates, or lacks power
  • Exhaust leak
  • Failed emissions test

How does a technician diagnose code P0136?

If a diagnostic scan of your vehicle indicates a code P0136, a technician will perform tests to pinpoint the problem. These tests include checking for any related trouble codes. The technician will also use the scan tool to read the live data from the oxygen sensors and make comparisons under various operating conditions. The wiring that leads to the sensor will also be inspected and tested, along with the sensor itself. The technician might even remove the sensor and check readings while it is outside of the vehicle. 

How serious is this code?

In most cases, a code P0136 will not cause immediate driveability issues. That said, driving your vehicle without a working post-catalyst oxygen sensor typically means that the ECM cannot monitor the efficiency of the catalytic converter. This will prevent your vehicle from passing an emissions test, but it is not dangerous for your engine. Have this code checked out in a week or so. 

Get this checked out soon by a CarAdvise shop, where the work will be guaranteed, and one of our expert techs will review any repair orders.


Related Diagnostic Trouble Codes

P0132 “O2 Sensor Circuit High Voltage (Bank 1, Sensor 1)”

P0137 “O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)”

P0138 “O2 Sensor Circuit High Voltage (Bank 1, Sensor 2)”


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