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  • The P0037 code stands for “Heated Oxygen Sensor (HO2S) Heater Control Circuit Low (Bank 1, Sensor 2),” which means there’s an issue with the heating element of the downstream oxygen (O2) sensor behind the catalytic converter.
  • A faulty O2 sensor and heater control circuit issues are some possible causes of the P0037 code.
  • Some common symptoms of the P0037 include an illuminated Check Engine Light and a failed emissions test.

For an engine to run efficiently, it must achieve the proper air-to-fuel ratio. The powertrain control module (PCM) determines how much fuel gets injected into the engine. It calculates the correct levels with the help of the sensors installed around the engine. One of the most important sensors for its operation is the oxygen (O2) sensor.

There is one oxygen sensor before the catalytic converter (referred to as sensor 1) and another located after the catalytic converter (referred to as sensor 2). The PCM uses the signal from sensor 1 when calculating fuel delivery. On the other hand, the module primarily uses the signal from sensor 2 when determining the status of the catalytic converter.

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Each oxygen sensor must warm up to work properly and relay accurate information. Inside the sensor is a heater wire that helps it come up to its working temperature quicker. When the PCM detects a problem with the heater control circuit of the rear oxygen sensor, on-board diagnostics will log a P0037 code.

oxygen sensor automotive image
Code P0037 refers to a malfunction in the heating element of the downstream oxygen sensor behind the catalytic converter.

What Does the P0037 Code Mean?

Diagnostic Trouble Code (DTC) P0037 stands for “Heated Oxygen Sensor (HO2S) Heater Control Circuit Low (Bank 1, Sensor 2).” It refers to a malfunction in the heating element of the downstream oxygen sensor behind the catalytic converter.

While it is generic to vehicles from different auto manufacturers, the steps for diagnosis and repair for a code P0037 for a Nissan may vary from that of a Ford.

If you’re trying to figure out where Bank 1 is, read our guide here. To understand why oxygen sensors need to be heated, you can read our technical explanation here. Otherwise, you can proceed to the next section to quickly learn the possible causes of code P0037.

What are the Possible Causes of the P0037 Code?

  • Defective oxygen sensor
  • Malfunctioning PCM heater circuit
  • Heater control circuit issues, such as damaged wiring and poor connections

What are the Common Symptoms of the P0037 Code?

A malfunction in the oxygen sensor heater control circuit will not prevent your vehicle from operating. However, you may experience the following symptoms.

See also  P0136 Code: O2 Sensor Circuit (Bank 1, Sensor 2)

Take note that if the check engine light is on, your car will automatically fail an emissions test.

car emission test
You will fail an emissions test if your check engine light is on.

How to Diagnose the P0037 Code

A problem with your downstream oxygen sensor typically triggers the P0037 code. However, diagnosing this issue might be tricky. If you’re not very confident with your automotive DIY skills, you might be better off leaving the diagnosis to a mechanic.

Of course, you can still do the troubleshooting yourself, but you should watch the video below to find out what the process might involve.

How to Fix the P0037 Code

Fixing the P0037 code is not as straightforward as you might think since there are several possible reasons that could have triggered it in the first place. This is why having a professional mechanic do the job is a good idea.

However, you can still do the fixing yourself if you have the necessary automotive DIY skills. You may need the help of online auto repair resources and guides to figure out the appropriate fix for your car. You can also get an ALLDATA single-vehicle subscription, which should help you with this fix and other future fixes you may need to do on your car.

Just remember to consult your owner’s manual before working on your car.

Where to Get a New Oxygen Sensor for Your Vehicle

You can still drive around with a faulty O2 sensor, but is the risk really worth it? You’re likely to end up with engine performance issues, such as misfiring, rough running, and stalling. A faulty O2 sensor can also cause poor fuel economy, which means you’re paying for a lot more gas than you need to. Luckily, you can avoid all that by easily buying a new O2 sensor at 

See also  P0137 Code: Oxygen Sensor Circuit Low Voltage (Bank 1, Sensor 2)

Get a quality replacement by browsing through products we sourced from only the most trusted manufacturers in the industry. You don’t have to worry about long wait times either. With strategically located warehouses all over the US, guarantees fast shipping. You can get your new O2 sensor in as fast as two business days. 

Don’t wait until your O2 sensor starts causing problems for you and your engine. Check out our wide selection of quality O2 sensors today here at

Products Mentioned in this Guide

About The Authors
Written By Automotive and Tech Writers

The Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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My car is Toyota corolla 2009. How can locate d sensor 2 bank 1


My car is 2011 lincoln town car. Where can I locate os2 oxign sensor heater resistance bank 1 and 0s2 sensor heater resistance circuit?

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