What the OBD-II code p0037 means

Fault code P0037 – a step-by-step guide to diagnosing and fixing it

The meaning of error code P0037 – HO2S Heater Control Circuit Low (Bank 1, Sensor 2)
P0037
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P0037: causes, symptoms and repairs

The meaning of fault code P0037

DTC P0037 is set when the signal voltage in the heater circuit of oxygen sensor 2 (cylinder bank 1)is lower than it should be. The heated device is located downstream of the catalytic converter and is used to determine the concentration of oxygen in the exhaust system. It has its own heating system so that it can reach the operating temperature quickly, shortening the time it takes for the engine to enter a closed cycle. When the engine control module (ECM) isnt receiving accurate information from the O2 sensors, it cannot achieve an optimal air-fuel ratio.

Common causes of code P0037

  • Broken wires or short circuits. Electrical faults can occur when the insulation sheath of the wires is damaged or fraying.
  • Corroded electrical contacts. Corrosion is the result of exposure to dirt and moisture.
  • A loose or damaged connector, affecting the sensor signals. Over time, the connector wire can crack or break. Excessive vibration or rubbing can cause damage such as fretting corrosion.
  • A faulty heater. There may be permanent circuit damage or high resistance. The heating element can burn out when the catalytic converter or electrical wiring goes bad, or due to sudden changes in temperature.
  • Using an oxygen sensor that does not comply with the vehicles specifications. This should be noticeable shortly after the component has been installed.
  • A bad ECM, generating false DTCs. This is a much less common problem.
Symptoms to look out for

  • Activation of the check engine light
  • A rough or sluggish engine
  • A poor fuel economy
  • Decreased engine power
  • A fuel or sulphur smell coming from the exhaust
Recommended repairs

  • You cannot repair the vehicle without a proper diagnosis of the problem. Scan the vehicles onboard computer with an OBD2 scanner to see which DTCs are present and to check the freeze frame data. This will help you to quickly find the cause of the fault.
  • Inspect the sensor components and wiring for damage. If there are visible cracks, bent or broken parts, or melted or frayed wires, replace the damaged components. Make sure that the wires and connectors are properly attached and routed away from the exhaust system to prevent thermal damage. Corroded electrical contacts will need to be cleaned and treated using special products to restore the electrical connection and prevent further corrosion.
  • You can test for internal faults or short circuits using a multimeter or voltmeter. While the engine is off and sensor is disconnected, check the voltage coming through the B+ battery feed. This should be around 12V. If the readings are abnormal or no voltage is detected, it indicates that theres a short or broken circuit. Install new components to fix the unit. You should also measure the resistance of the ground circuit.
  • If no shorts or opens are detected and the scan data indicates a power or signal problem, it is likely that the heated O2 sensor is failing. Follow the vehicle manufacturers instructions and install a new one.
  • Make sure that the catalytic converter and other vital exhaust and engine components are functioning properly. Replace them if necessary. Check catalytic converters for sale here.
Frequently Asked Questions (FAQ)

What does the code “P0037” mean?


It means that the ECM has detected that the voltage signal from the oxygen sensor 2 heater circuit is below the normal range.

What causes it?


It is often caused by broken wires, a short ground or feed circuit, corrosion, loose connections or a defective heater or sensor.

How serious is the fault?


It will not stop the car from moving or pose an immediate risk to your safety, but it may stop the vehicle from passing an emissions test. It is advisable to get it fixed as soon as possible to avoid extensive damage and keep the engine running efficiently.

Cars the fault code P0037 is most commonly found on

Fault code P0037 - HO2S Heater Control Circuit Low (Bank 1, Sensor 2) can occur with any car but is most often found on the following cars:

  • Toyota: Prius, Avensis
  • Nissan: Micra
  • Mazda: MX5, RX8, 3
  • Jaguar: X Type
  • Peugeot: 208
  • Lexus: IS300

If you get the code P0037 on your car, make sure that the diagnostics are carried out correctly and the error is still relevant. Check for symptoms associated with the problem and explore options for resolving it.

What to do if the fault code p 0037 appears

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