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P0137 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


Trouble code P0137 on your OBD-II sensor means that your O2 sensor circuit is experiencing low voltage, located in Bank 1, Sensor 2.


P0137 is the OBD-II generic code that indicates the O2 sensor for bank 1, sensor 2 is failing in order to increase the voltage output to above .21 volts. This indicates that there is excessive oxygen in the exhaust.


There are several different factors that can cause a P0137 OBD-II generic code. This can be due to the fact that the ECM senses the low voltage problem, triggering the Check Engine Light to turn on. It could also be due to the fact that the ECM uses other O2 sensors to try and control the fuel injection, and their values. This problem and this trouble code can also be triggered by leaks in the exhaust.


There are a few key symptoms that you should be looking for that will help indicate if a P0137 trouble code is present. The engine will run rich at the time that you are testing the sensor for a problem. As with most of these codes, code P0137 should cause your check engine light to become illuminated. If this is in fact the specific problem you are facing, you may notice that the exhaust leaks just before or near the O2 sensor that is in question.


It is very important when you are confirming a P0137 OBD-II generic code that you follow each of the below steps for diagnosing the problem diligently and in order:


  • Scan codes and documents. Here’s a great one we use daily. Make sure that you freeze frame data and then clear the codes to verify failure.
  • Monitor the O2 sensor data to see if the voltage is switching back and forth between low and high. You should look to see if this is occurring at a faster rate when compared to other sensors.
  • Check the O2 sensor harness connections and wiring for any corrosion in the connections.
  • Next, check the O2 sensor for any physical damage or fluid contamination.
  • Examine closely for exhaust leaks that occur before the sensor.
  • When in doubt, follow the manufacturer’s specific pinpoint tests for further diagnosis.

Common mistakes

If you follow the above steps, you should have no issues in properly diagnosing a P0137 OBD-II generic code. Be sure to follow these simple guidelines to prevent a misdiagnosis of the problem:

  • Repair any exhaust leaks before the sensor. This will prevent excess oxygen from getting into the exhaust stream, which causes the low voltage readings.
  • Check the O2 sensor for coolant or oil contaminants that could foul the sensor.
  • Repair any harness that is damaged properly. This will prevent erratic readings that you can pick up from the sensors.
  • Check the removed O2 sensor for damage from a broken catalyst. Replace the catalyst if it has come apart.

How serious is this?

Though a P0137 may not cause immediate problems or damage to your vehicle, it can eventually lead to that. If you let the problem go unaddressed, it can eventually lead to the premature failure of certain components within the engine. This is why it is imperative that you get this problem fixed sooner than later.

  • The voltage output from the O2 sensor may be present because of exhaust leaks that cause the O2 sensors to give low output voltages.
  • The ECM cannot correctly control the fuel-to-air ratio of the engine fuel mixture if any O2 sensor is malfunctioning. This will lead to poor fuel mileage and possible premature failure for some engine components.

What repairs can fix the code?

There are a few key repairs that can fix the P0137 code.

  • Make sure you replace the O2 sensor for bank 1, sensor 2.
  • Repair or replace the wiring or connection to the O2 sensor for bank 1, sensor 2.
  • Repair any and all exhaust leaks before the sensor.

Related codes

None listed.


If you believe that a vehicle is experiencing symptoms that are indicative of a P0137 code, you can use this as a guide to confirm the issue and your findings. Although this trouble code will not make the vehicle inoperable, it can cause further damage to certain engine components, making for more expensive and more frequent repairs in the future.

P0137 Code – What Does It Mean & How To Fix It