Code Definition

P1154 — Heated Oxygen Sensor 1, bank 2 - slow response

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Hyundai

About P1154

P1154 is a manufacturer-specific powertrain diagnostic trouble code recorded for Hyundai vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1154 is stored, the module has detected a signal or supply voltage lower 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.

P1154 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The upstream heated oxygen sensor for Bank 2 Sensor 1 switches rapidly between rich and lean as the Engine Control Module cycles fuel around the stoichiometric point on the second cylinder bank. DTC P1154 is set on Hyundai and Kia vehicles when this sensor responds too slowly, its switching frequency and transition speed falling below the threshold expected during closed loop operation. As with the Bank 1 equivalent, a slow or lazy sensor usually results from age, contamination, or a heater circuit that is slow to reach operating temperature. The code mainly affects fuel control accuracy on Ba...

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