Code Definition

P0044 — HO2S Heater Control Circuit High (Bank 1 Sensor 3)

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

About P0044

P0044 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 P0044 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 P0044 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 P0044 sets when the Engine Control Module detects a high voltage or open condition in the heater control circuit of the oxygen sensor in the bank 1 sensor 3 position, the third sensor in the bank 1 exhaust on vehicles with extra post catalyst monitoring. The heater brings the sensor to operating temperature quickly so it gives a stable signal, 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 control wir...

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