Code Definition

P1191 — Fuel Trim Error - Bank 2, Sensor 1

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

About P1191

P1191 is a manufacturer-specific powertrain diagnostic trouble code recorded for BMW vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1191 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.

P1191 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) continuously trims the air to fuel mixture using feedback from the upstream oxygen sensor on Bank 2, storing these corrections as short term and long term fuel trim values. DTC P1191 is set when the ECM finds that the fuel trim correction required on Bank 2 has moved beyond the permissible range, meaning the system can no longer hold the mixture close to the ideal ratio. On this BMW application the fault usually reflects a genuine lean or rich condition on the bank feeding Sensor 1 rather than a fault in the sensor itself. The driver may notice rough or unstable...

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