P0037 OBD2 Trouble Code – Check the O2 sensor and wiring!

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P0037 OBD2 Trouble Code


Meaning of P0037 OBD-II Code

The technical definition of P0037 is: HO2S Heater Control Circuit Low Bank 1, Sensor 2

Pro Tip
The P0037 OBD2 Trouble Code means there is a problem with the heater circuit in the #2 oxygen sensor, which is usually located to the rear of the catalytic converter.

Depending on the make and model of your vehicle, the P0037 code may also mean a couple of things like a broken 12-volt battery connector, bad grounding, or a faulty internal heater element. If the check engine light is not caused by a minor electrical fault, the main problem can be traced to #2 O2 sensor in bank 1.

CarsNToys did a good video on troubleshooting this generic DTC on a 2010 Subaru:

What causes P0037 fault code?

This code is associated with the heater element in the #2 oxygen sensor. It may or may not have to do with the actual O2 sensor. In some cases, the O2 sensor is okay but the heater element is starting to fail. Use a Digital Mulimeter to help you troubleshoot the cause of this code.

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DTCs like P0038, P0037, P0031 are often seen together when you’re having O2 sensor issues. You may see one or multiple at the same time.

  • 12-volt battery connector
  • Poor grounding
  • Faulty internal heater element
  • Bad O2 Sensor

In order to maintain an efficient combustion, the heated oxygen sensors are responsible for detecting the oxygen content in the exhaust. The ideal air-to-fuel ratio is 14.7 to 1, which the ECM adjusts accordingly depending on the O2 sensor readings.

The P0037 trouble code is usually triggered during cold starts. The heated O2 sensors rely on heating elements to maintain a correct reading when the engine is cold. If the ECM detects an abnormal O2 sensor reading in closed loop mode, the check engine light will activate to display the code.

P0037 fault code DTC explained

What are the symptoms of P0037 DTC?

Besides the presence of a check engine light, the generic DTC will cause a variety of combustion problems. Since the ideal air-fuel ratio is not consistently maintained by the motor, a P0037 fault code will cause rough idling and hesitation. In vehicles equipped with automatic transmissions, you will also notice abrupt shifting patterns and a general sensation of roughness at medium to high speeds.

  • Rough Idling
  • Hesitation
  • Hard Shifting

However, the symptoms of this code will depend on the make and model of the vehicle. In some cases, engine stalling is also a common issue. There are some vehicles that will only reveal a check engine light when the engine is cold. The check engine light will turn OFF once the motor reaches the desired operating temperature.

How much does it cost to fix P0037 OBD2 code?

It depends on the severity of the problem. Since a P0037 code can be triggered by a faulty electrical system, fixing frayed or broken wires and loose connectors will only cost $10 to $20.

On the other hand, the O2 sensor will need to be checked as well. The worst case scenario is replacing the heated oxygen sensor, which will run from $50 to $120 depending on the vehicle type.

But don’t fret. Most of the problems associated with a P0037 DTC is usually related to wiring or electrical issues, especially on older vehicles. Since the location of the heated oxygen sensor is constantly exposed to heat from the exhaust, the wiring, sockets, and electrical connectors are prone to damage as well.


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