Code Definition

P0037 — HO2S Heater Control Circuit Low (Bank 1 Sensor 2)

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P0037

P0037 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P0037 is stored, the module has detected a signal or supply voltage lower than the expected operating range; a bank-specific fault, meaning it applies only to one cylinder bank of a multi-bank engine; and a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P0037 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

DTC P0037 sets when the Engine Control Module detects a low voltage or high current condition in the heater control circuit of the downstream oxygen sensor on bank 1 sensor 2, the sensor mounted after the catalytic converter. The heater element brings the sensor to operating temperature quickly so the ECM can read a stable signal to monitor catalyst efficiency, and the ECM switches it through a low side driver while watching the circuit. The Low code specifically points to the control circuit being pulled low, most often a short to ground in the heater wiring, a heater element shorted internal...

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