Code Definition

P1166 — Heated Oxygen Sensor front bank 1 control limit

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

About P1166

P1166 is a manufacturer-specific powertrain diagnostic trouble code recorded for Kia vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1166 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.

P1166 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 Engine Control Module (ECM) runs a closed loop lambda control routine that uses the front bank 1 heated oxygen sensor to keep the air fuel mixture near the ideal ratio by continuously trimming injector delivery. DTC P1166 sets when the lambda controller reaches its maximum or minimum correction threshold and can no longer pull the mixture back to target, and no proportional fuel adaptation occurs within the defined time. In practice the ECM is commanding as much fuel correction as it is allowed but the measured mixture stays too rich or too lean. This usually reflects a real fuelling or ai...

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