Code Definition

P1145 — O2 Sensor Sluggish (Slow Cross-counts) (Bank 1 Sensor 3)

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

About P1145

P1145 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 P1145 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.

P1145 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 Bank 1 Sensor 3 oxygen sensor, the third sensor located far down the exhaust on vehicles with an additional catalyst section, is switching too slowly. The PCM watches how quickly this sensor crosses its switching threshold during the rationality test and counts the transitions over time. P1145 sets when the cross counts and response speed fall below the threshold, meaning the sensor is sluggish and no longer reacting promptly to changes in the exhaust. Because Sensor 3 plays only a supporting role, the driver rarely notices a symptom, although...

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