DTC P1111: IAT SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE Isuzu Amigo II

Note. For circuit reference (Схема №3)

Circuit Description

Intake Air Temperature (IAT) sensor is a thermistor. PCM applies and reads a 5-volt reference signal to sensor. When air is cold, sensor resistance is high and PCM will measure a high signal voltage. If air is warm, sensor resistance is low causing PCM to measure low voltage.

Conditions required to set DTC are

1. Engine running for more than 4 minutes.
2. No ECT, MAF or VSS sensor DTCs set.
3. Vehicle speed is less than 20 MPH.
4. MAF less than 20 grams per second.
5. ECT is greater than 140°F (60°C).
6. IAT signal voltage intermittently indicates IAT less than - 38°F(-39°C) about 5 volts, for 2.5 seconds over a 25-second period.

Diagnostic Aids

Check for faulty connections or damaged harness. Observe IAT display on scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location. Check for skewed IAT sensor. See IAT SENSOR RESISTANCE . If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.