Code Definition

P1118 — Manifold Air Temperature circuit low input

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

About P1118

P1118 is a manufacturer-specific powertrain diagnostic trouble code recorded for Ford vehicles. 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

The P1118 code sets when the PCM sees the Manifold Air Temperature (MAT) sensor signal voltage below the calibrated threshold for a valid reading. The MAT sensor is a negative temperature coefficient thermistor that measures the temperature of air in the intake manifold, and its signal voltage falls as that air gets hotter. A low input therefore corresponds to an implausibly high indicated manifold air temperature, which normally points to a short to ground in the signal circuit or a sensor that has failed with very low resistance rather than genuinely hot air. Acting on a false high air tempe...

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