P1109
Intake Air Temperature Sensor 2 Intermittent
Findings, check these first
- Loose IAT2 connector at the intercooler outlet
- Heat-damaged IAT2 wiring
- Failing IAT2 sensor
- Corroded terminals
- PCM reference fault
Standard procedure
- Locate the post-intercooler sensor and inspect its connector
- Wiggle-test while watching live IAT2
- Compare IAT2 to IAT1 on a cold engine
- Check terminals for heat damage
- Replace the sensor if dropouts persist
Code lookup
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Sources and review
Review: checked against the recorded source material.
- OBDII.pro: P1109 Ford definition
live reference page (obdii.pro)
Supports: Ford-family meaning for P1109: IAT - B Sensor Intermittent
Fetched directly. obdii.pro is a publisher independent of the engine-codes family.
- P1109 FORD Code: Meaning, Causes, and Symptoms | OBD2 Codes
live reference page (obd2-codes.co)
Supports: Ford meaning for P1109: IAT Sensor 2 Intermittent Condition
Fetched directly. obd2-codes.co phrasing matches the engine-codes family, so it counts as one publisher.
Last updated 2026-09-05.
Report a correction for P1109. Include your vehicle, the issue and a source if you have one.
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