Code Definition

P0038 — HO2S Heater Control Circuit High (Bank 1 Sensor 2)

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

About P0038

P0038 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 P0038 is stored, the module has detected a signal or supply voltage higher 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 P0038 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 P0038 sets when the Engine Control Module detects a high voltage or open 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 with a low side driver while watching the circuit voltage. The High code points to the control side sitting higher than expected, typically an open heater element, an open or high resistance in the heater ground or cont...

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