Code Definition

P1140 — O2 Sensor Sluggish (Bank 1 Sensor 2)

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

About P1140

P1140 is a manufacturer-specific powertrain diagnostic trouble code recorded for GM vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1140 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.

P1140 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

This General Motors specific code reports that the downstream oxygen sensor on Bank 1 Sensor 2, located after the catalytic converter, is responding too slowly. The PCM monitors the rear sensor both to fine trim fuel and to judge catalyst efficiency, and it expects the sensor to respond within a set time when the mixture is deliberately varied. P1140 sets when the Bank 1 Sensor 2 response is sluggish, taking longer than the threshold to react during the sensor rationality test. Because the rear sensor has only a small effect on running, there is often no driveability symptom, although fuel eco...

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