2000 Chevy Malibu Problem

[mstngcobrasvt98]

I brought it into the shop to see why the check engine light was on and the mechanic told me it was an "Intake Air Temp High" or code P01189 I believe. What is this saying is wrong or needs to be fixed?

[nagel83]

so ive taken my malibu in 3 times. the first time that i took it into a major dealership -- where i bought my car... they told me that the sound was the alternator... they fixed for not cost to me. then i took it in again.. they told me that it was a noise that malibus make when they are cold... very loud... can anyone else respond to this or am i alone???

[e2helper]

Actually I think P1189 is Engine Oil Pressure Switch Circuit. Intake Air Temp High is P1111.

For IAT P1100:
The intake air temperature (IAT) sensor is a thermistor which measures the temperature of the air entering the engine. The Powertrain Control Module (PCM) applies 5.0 volts through a pull up resistor. When the intake air is cold, the sensor resistance is high and the PCM will monitor a high signal voltage on the IAT sensor signal circuit. As the intake air warm, the sensor resistance becomes lower causing the PCM to monitor a lower voltage. If the PCM detects an excessively high IAT Sensor signal voltage (low temperature indicated), the DTC will set.

If it is P1189:
The low oil pressure sensor is normally closed. When oil pressure increases above 1 to 4.5 psi the switch contacts open. The PCM supplies 12 volts to the oil pressure input circuit. With low oil pressure the 12 volts is pulled low to ground. This diagnostic tests for a open condition of the oil pressure switch circuit. If the engine has been off long enough for engine temperature to drop by 10°C, then a shorted (low oil pressure) condition of the circuit should be observed prior to engine running. If the engine has not been cranked and oil pressure has been detected. DTC P1189 will set.

In either case diagnostic procedure would tell you first to be looking for an open circuit somewhere on wiring between these sensors and the engine controller.