Code Definition

P0056 — HO2S Heater Control Circuit (Bank 2 Sensor 2)

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

About P0056

P0056 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 P0056 is stored, the module has detected 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 P0056 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

The P0056 code indicates a malfunction in the heater control circuit of the oxygen sensor located in Bank 2 Sensor 2. This sensor is a downstream sensor, positioned after the catalytic converter. The heater circuit in the oxygen sensor is important for bringing the sensor up to its operating temperature quickly after the engine starts. The Engine Control Module (ECM) sets this code when it detects an issue in the heater circuit, which can affect the sensor's ability to accurately monitor the exhaust gas for optimal fuel management.

Quick Facts