Code Definition

P1159 — O2 Sensor Cross-counts (Bank 2 Sensor 2)

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

About P1159

P1159 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 P1159 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.

P1159 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 relates to the cross counts, or number of rich to lean transitions, recorded by the Bank 2 Sensor 2 downstream oxygen sensor. A healthy post catalyst sensor should be relatively steady because the converter buffers the exhaust, so it crosses its switching threshold only slowly. P1159 sets when the PCM counts the Bank 2 rear sensor crossing too often, behaving more like an upstream sensor than a rear one. Excessive cross counts usually point to a catalyst that is no longer storing oxygen on that bank, an exhaust leak near the sensor, or a sensor and wiring faul...

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