Solved: temperature sensor

Friday, February 24, 2012

Intake Air Temperature (IAT) Sensor operation?

Intake Air Temperature (IAT) Sensor operation dtails are as follows ;---

OPERATION

The Intake Air Temperature (IAT) sensor is a thermistor which changes value based on the temperature of the air entering the engine. Low temperature produces a high resistance (100,000 ohms at -40°F.) while high temperature causes low resistance (70 ohms at 266°F.). The PCM supplies a voltage (about 5.0V) through a pull up resistor to the PCM's IAT signal circuit and measures the voltage. The voltage will be high when the in coming air is cold, and low when the air is hot. By measuring the voltage, the PCM calculates the in coming air temperature. The IAT sensor signal is used to adjust spark timing according to incoming air density.

A technician's scan tool displays the temperature of the air entering the engine, which should read close to the ambient air temperature when the engine is cold, and rise as the underhood temperature increases. If the engine has not been run for several hours (overnight), the IAT sensor temperature and engine coolant temperature displays should be close to each other. A failure in the IAT sensor circuit should set a Diagnostic Trouble Code.

This will help.
Thanks.

Tuesday, October 25, 2011

Replacing temperature sensor on AUDI 1.9 TDI?

The sensor is located on back of cylinder-head near by vacuum-fuel double pump. There is an assurance clip and a rubber sealing O-ring. Heed of antifreeze solution temperature!!!
Before you try to change the sensor you must be sure that the sensor is out of order. First you must check the thermostat operating. Thermostat checking:
1. Cold engine. Start up the engine and watch of the water temp indicator. After first value 60 Celsius Degree you still warm up the engine until the lifter (pointer) reach 80 C deg. (second mark after 60 C deg.). At this time you let engine running at idle speed and check with your hand the thermostat plastic housing and hose temperature in bottom left side of the engine. Heed of alternator driving belt and ventilator fan !!!
2. If the thermostat is good the hose must be cold until the water temp indicator reach almost 90 C deg.
3. The thermostat opening temperature is 87 C deg.
4. If the hose is already warm the thermostat is out of order.
5. If the thermostat and the temp sensor are OK the last piece out of order will be the instrument cluster.

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For more car related problem troubleshooting:---

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