Code Definition

P1135 — O2 Sensor 1 Bank 1 Reading Lean, or 4/5 Shift Solenoid Stuck On

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

About P1135

P1135 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 P1135 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.

P1135 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 has two platform dependent definitions, the Bank 1 upstream oxygen sensor reading persistently lean, or the 4/5 shift solenoid in the automatic transmission staying on when it should be off. In the oxygen sensor form, P1135 sets when the PCM sees the Bank 1 Sensor 1 signal biased toward the lean end, staying low in voltage and failing to swing rich during closed loop, which can flag a genuine lean mixture or a skewed sensor. In the transmission form, the code reports that the 4/5 shift solenoid is electrically or hydraulically stuck on, which disturbs the norm...

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