The OBD2 error P0037 code is a generic trouble code that indicates a problem with the oxygen sensor heating element for the sensor installed in the bank 1 sensor 2 position. The oxygen sensors are responsible for maintaining a 14.7/1 air/fuel ratio and monitoring the condition of the catalytic converter. This sensor is located behind, or downstream, of the catalytic converter, monitoring the condition of said converter. For the oxygen sensor to transmit the proper data to the ECM it needs to reach operating temperature as soon as possible. The heating element heats the sensor when it is below temperature to speed up the process and allows the vehicle to reach closed loop.
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P0037 Code Definition
P0037 (Generic): HO2S Heater Control Circuit Low (Bank 1, Sensor 2)
What Does P0037 Mean?
Vehicles produced after 1996 and sold in the United States are required to be OBD-II compliant to meet federal emissions requirements. Part of meeting OBD-II standards is having a catalytic converter that is monitored by a downstream oxygen sensor. The oxygen sensor can detect the amount of oxygen in the exhaust stream allowing the ECM to make adjustments to the amount of fuel injected into the combustion chamber. This is important because for the catalytic converter to function properly it needs to have a near perfect air/fuel ratio. This is the primary responsibility of the sensor located upstream of the catalytic converter.
The sensor mounted downstream of the catalytic converter is mainly responsible for verifying the function of the converter. This sensor reads the amount of oxygen left over after the exhaust stream has passed through the catalytic converter. For oxygen sensors to accurately report information to the ECM they need to be at full operating temperature. Each sensor is equipped with a heating element to help speed up this process. Trouble code P0037 refers to a problem involving the heating element inside the oxygen sensor.
What Are The Symptoms Of The P0037 Code?
The P0037 trouble code will generally not have any other symptoms other than an illuminated check engine light.
What Are The Causes Of P0037?
- Faulty oxygen sensor heater
- Damaged wiring
- Failed ECM
How Serious Is The P0037 Code?
P0037 is not a serious trouble code. Generally speaking, you will not notice any drivability symptoms with this code. However, by having an oxygen sensor heater that is not operating properly, you will be releasing more harmful vehicle emissions into the atmosphere than allowed by federal emission standards.
How To Diagnose And Fix The P0037 Trouble Code
The P0037 trouble code is usually a straight forward diagnosis and repair. The first step is to use your OBD-II scan tool to scan and record any trouble codes. Even if you have other codes related to the vehicles oxygen sensors, starting with a diagnosis of P0037 is recommended.
Once you have recorded all of the vehicles trouble codes, consult service information to locate the oxygen sensor located in the bank 1 sensor 2 position. Once you are certain you are dealing with the correct sensor, give the sensor and associated wiring a thorough visual inspection. It is common to have physically damaged sensors and wiring due to the vulnerable location.
If nothing is found during the visual inspection, consult a wiring diagram to find the proper wires for the power and ground circuits to the oxygen sensor heater. Unplug the sensor and using a multimeter, check for resistance across the heating element on the sensor side of the wiring harness. If this results in an open circuit or no resistance, it means that the heating element is open inside the sensor. If this is the case, replace the sensor and clear trouble codes. If your meter shows an ohm value, check the specifications in your service manual.
If the heating element is within the specified resistance values, use your wiring diagram to test the power and ground circuits to the oxygen sensor heater. Depending on the vehicle, the ECM either supplies a 12 volt signal or a ground to the heating element. If you have an advanced OBD-II scan tool you may be able to perform a functional test and activate the heater manually to check the power and ground circuits. If not, you will need to test after a cold soak, as the ECM will not activate the heater if the sensor is already warm. If you are missing either of these signals, trace the circuit until the problem is found. In rare cases, the driver in the ECM can be defective and not send out the power or ground signal to the sensor. If this is the case, replace the ECM.
Common Mistakes To Avoid While Diagnosing The P0037
To avoid common mistakes, make sure the follow the diagnostic procedure. While a failed oxygen sensor is the most common cause of P0037, it is important to verify the heater circuit before replacing the sensor.