Skip the auto shop - Our mechanics make house calls

P0136 OBD-II Trouble Code: O2 Sensor Circuit Malfunction (Bank 1, Sensor 2)

Check Engine Light

P0136 code definition

O2 Sensor Circuit Malfunction (Bank 1, Sensor 2)

What the P0136 code means

P0136 is the OBD-II generic code indicating the downstream O2 sensor for bank 1 fails to meet the minimum and maximum voltage limits calibrated for the ECM to see.

What causes the P0136 code?

  • The ECM monitors the O2 sensor’s highest and lowest voltages. This code occurs when the voltage limits are not within specifications programmed into the ECM.

  • The ECM detects a voltage problem and turns on the Check Engine Light.

  • The ECM uses other O2 sensors to try and control the fuel injection with known values.

  • There is an exhaust leak or catalyst failure in front of the sensor.

What are the symptoms of the P0136 code?

  • The engine may run excessively rich if the engine goes into open loop.

  • The engine may start to misfire if the spark plugs get fouled out over time.

  • The Check Engine Light will be illuminated.

  • You may have exhaust leaks or loss of power from a clogged or bad catalyst.

How does a mechanic diagnose the P0136 code?

  • Scans codes and documents freeze frame data then clear codes to verify failure

  • Monitors O2 sensor data to see if the voltage is switching back and forth between low and high at a fast rate compared to other sensors

  • Checks the O2 sensor wiring and the harness connections for any corrosion

  • Checks the O2 sensor heater circuit for the proper resistance to specifications

  • Checks for exhaust leaks before the sensor

  • Follow the manufacturer's specific pinpoint tests for further diagnosis.

Common mistakes when diagnosing the P0136 code

Follow these simple guidelines to prevent misdiagnosis:

  • Repair any exhaust leaks before the sensor to prevent incorrect readings.

  • Check the O2 sensor for oil or coolant contaminants from engine leaks.

  • Repair any harness that is damaged properly without taking shortcuts to prevent repeat failures.

  • Check the removed O2 sensor for damage from a defective catalyst and replace the catalyst if it is faulty.

How serious is the P0136 code?

  • The voltage output from the O2 sensor may point to engine and exhaust problems causing the O2 sensors to give erratic output voltages.

  • The O2 sensor may not read correct if the catalyst is damaged in front of the sensor.

  • The ECM may stay in open loop until the O2 system is repaired or the O2 sensor starts working again causing extended rich conditions that could possibly damage other engine components.

What repairs can fix the P0136 code?

Additional comments for consideration regarding the P0136 code

The O2 sensor circuit for bank 1 sensor 2 is used to give a voltage feedback to the ECM to control the fuel and provide information about catalyst operation.

Need help with a P0136 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

How to Transfer a Car Title in Idaho
In order to prove ownership of a car, you must have the title. However, when a car is sold, given away or inherited, the title needs...
Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...


Related questions

Q: Service engine warning, MAF code and O2 sensor code, along with check suspension light are turned on

Hello, it sounds like you have quite a few things going on. I am going to do my best to break them down for you. First if the engine is very loud when idling and the belt has...

Q: On slow moving traffic, when i release the brakes, the car has lags for half a second before take off... computer scan shows p2138

This code is related to a faulty throttle position sensor. The throttle position sensor (TPS) is a sensor used to monitor the throttle position of a vehicle. The sensor is usually located on the butterfly spindle/shaft so that it can...

Q: My engine light turns on, and i went to autozone to diagnosis, and it's faulty o2 sensor. Would you be able to replace it?

If code P0136 sets the only way you can determine if the oxygen sensor has failed is to use an automotive scope to graphically depict the sensor output waveform (it will look roughly like a sine wave) and switching rate...