Code Definition

P1118 — Manifold Absolute Temperature Circuit Low Input

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

About P1118

P1118 is a manufacturer-specific powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1118 is stored, the module has detected a signal or supply voltage lower than the expected operating range.

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.

P1118 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 fault code is set when the Powertrain Control Module (PCM) detects a low voltage signal from the Manifold Absolute Temperature (MAT) sensor. The MAT sensor measures the temperature of the air inside the intake manifold, helping the PCM adjust fuel delivery and ignition timing. A low input signal typically indicates a short to ground or a faulty sensor.

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