P0111 - Intake Air Temperature Sensor Performance: Notes
Theory of Operation
Intake Air Temperature Sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. Following a start to run delay time, the outputs of the Ambient, Engine Coolant and Intake Air Temperature sensors will be compared. If the Engine Coolant and Ambient Air Temperature Sensors agree, and the Intake Air Temperature does not agree, the Intake Air Temperature Sensor is declared as irrational. If declared irrational a second comparison will be done after a short drive cycle.
- >>When Monitored:<< With the engine off time greater than 480 minutes and ambient temperature greater than -7°C (19.4°F).
- >>Set Condition:<< After a calibrated amount of cool down time, the Powertrain Control Module (PCM) compares the Ambient Air Temperature (AAT), Engine Coolant Temperature (ECT), and Intake Air Temperature (IAT) Sensor values. If one sensor value is not within 10°C (18°F) of the other temperature sensors for two consecutive trips, a DTC will set. Three good trips to turn off the MIL.
| Possible Causes |
|---|
| (K21) IAT SIGNAL CIRCUIT SHORTED TO VOLTAGE |
| (K21) IAT SIGNAL CIRCUIT SHORTED TO GROUND |
| (K21) IAT SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUND CIRCUIT |
| (K21) IAT SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE |
| (K900) SENSOR GROUND CIRCUIT OPEN OR HIGH RESISTANCE |
| INTAKE AIR TEMPERATURE (IAT) SENSOR |
| POWERTRAIN CONTROL MODULE (PCM) |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to Pre-Diagnostic Troubleshooting Procedure .