P1109 Possible Causes
- Outdated or incorrect Engine Control Module (ECM) software
- Faulty Engine Control Module (ECM)
How is P1109 Code Repaired?
Start by checking the “Possible Causes” listed above. Visually inspect the corresponding wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
Possible Symptoms
- Check Engine Light illuminated (or Service Engine Soon warning light)
- Irregular engine idle
- Engine hesitation
P1109 Meaning
The Barometric Pressure Sensor (BARO) is integrated into the Engine Control Module (ECM) and monitors atmospheric pressure. The ECM estimates the appropriate intake air flow from the Manifold Absolute Pressure (MAP) sensor output voltage and the BARO sensor output voltage. If the BARO sensor output voltage is at or above a specified value, the ECM detects a malfunction and a code is stored.