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

DTC P0038 indicates a high voltage condition in the heater control circuit of the downstream oxygen sensor on Bank 1 Sensor 2, the sensor located after the catalytic converter. This sensor uses an internal heater to reach operating temperature quickly after start up so it can accurately monitor catalyst performance, with the ECM controlling the heater on the ground side and watching the circuit voltage. P0038 sets when the ECM sees the heater circuit voltage stay higher than expected, which typically points to an open circuit or high resistance so the ECM cannot pull the circuit low, rather th...

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