P111D GMC Possible Causes
- Faulty Intake Air Temperature Sensor 1
- Intake Air Temperature Sensor 1 harness is open or shorted
- Poor electrical connection in the Intake Air Temperature Sensor 1 circuit
- Faulty Fuel Temperature Sensor 2
- Fuel Temperature Sensor 2 harness is open or shorted
- Poor electrical connection in the Fuel Temperature Sensor 2 circuit
How to Fix P111D GMC Code?
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
Engine Light On (or Service Engine Soon warning light)
P111D GMC Meaning
The Fuel Temperature Sensor 2 and Intake Air Temperature (IAT) Sensor 1 are variable resistors. The Fuel Temperature Sensor 2 is located on the fuel rail and the IAT Sensor 1 is part of the Mass Air Flow/Intake Air Temperature (MAF/IAT) sensor assembly. The Engine Control Module (ECM) provides 5V to the signal circuits and a ground for the low reference circuit of each sensor. The ECM monitors the Fuel Temperature Sensor 2 and IAT Sensor 1 circuits to calculate fuel and air temperature. The ECM monitors the Fuel Temperature Sensor 2 and IAT Sensor 1 signals for excessively high or low voltages, or for a voltage that does not correlate with the other sensor’s startup signal.