Code Definition

P1108 — BARO to MAP Sensor Circuit Comparison Too High

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

About P1108

P1108 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 P1108 is stored, the module has detected a signal or supply voltage higher than the expected operating range; 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.

P1108 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 code involves the Powertrain Control Module (PCM) comparing the Manifold Absolute Pressure (MAP) sensor signal against the Barometric Pressure (BARO) value. With the engine off and the key on there is no manifold vacuum, so the MAP reading should closely match barometric pressure, and the PCM uses this relationship to validate both readings for accurate engine load and altitude compensation. DTC P1108 sets when the MAP reading is too high compared with the expected BARO value, meaning the MAP signal is reporting more pressure than the atmospheric reference supports. Common triggers includ...

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