Code Definition

P1105 — Secondary Vacuum Sensor Circuit

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

About P1105

P1105 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 P1105 is stored, the module has detected 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.

P1105 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

On General Motors vehicles the P1105 code applies to the secondary vacuum sensor circuit, a sensor that reports manifold or system vacuum to the Engine Control Module (ECM) as part of the emissions and vacuum management strategy, often associated with EGR and secondary port throttle operation. The sensor is typically a three wire analog device supplied with a 5 volt reference, returning a signal voltage proportional to the vacuum applied to it. P1105 sets when the ECM sees the secondary vacuum sensor signal outside the expected range or implausible for the current operating conditions, which c...

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