Code Definition

P0038 — Oxygen Sensor 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

Bank 1 sensor 2 is the downstream oxygen sensor after the catalytic converter, and its internal heater brings the sensor up to operating temperature quickly so it can monitor catalyst efficiency soon after start up. The engine control module controls the heater through a driver circuit and monitors the voltage on that circuit. DTC P0038 sets when the ECM detects the heater control circuit voltage is higher than expected, which typically indicates an open circuit, a short to voltage, or a failed heater element. When the code is set the sensor takes longer to reach temperature, which can delay c...

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