P1111 ISUZU Intake Air Temperature Sensor Circuit Intermittent High Voltage

Possible causes

– Faulty Intake Air Temperature Sensor
– Intake Air Temperature Sensor harness is open or shorted
– Intake Air Temperature Sensor circuit poor electrical connection

When is the obd code mean?

The P1111 code is set when the Powertrain Control Module (PCM) senses a signal voltage higher than the normal operating range of the sensor.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P1111 ISUZU OBD Code Description

The Intake Air Temperature (IAT) sensor contains a semiconductor device which changes resistance based on temperature (a thermistor). The IAT sensor mounts in the air intake passage of the engine air induction system. The IAT sensor has a signal circuit and a ground circuit. The Powertrain Control Module (PCM) applies a voltage (about 5.0 volts) on the signal circuit to the sensor. The PCM monitors changes in this voltage caused by changes in the resistance of the sensor in order to determine the intake air temperature.

When the intake air is cold, the sensor (thermistor) resistance is high, and the PCMs signal voltage is only pulled down a small amount through the sensor to ground. The PCM senses a high signal voltage (low temperature). When the intake air is warm, the sensor resistance is low, and the signal voltage is pulled down a greater amount. This causes the PCM to sense a low signal voltage (high temperature).