Hyundai Coupes/Sedans 1994-1998 Repair Guide

Intake Air Temperature (IAT) Sensor

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OPERATION



The IAT is a thermistor (resistor) which changes valve based on the temperature it encounters. The IAT is mounted on the MAF sensor or air cleaner. Intake air temperature is an important parameter in fuel delivery calculations made by the ECM.

TESTING



See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: Intake air temperature sensor schematic-early model

Early Model With Six Terminal Connector

The early model IAT sensor is an integral part of the VAF sensor.

  1. Disconnect the sensor electrical harness.
  2.  
  3. Measure resistance between sensor terminals 4 and 6.
  4.  
  5. Resistance should be high when the ambient air is cold and steadily drop as the air warms.
  6.  

See Figure 2



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Fig. Fig. 2: Intake Air Temperature Resistance Chart

A hair dryer may be used to gently warm the sensor for testing purposes.

  1. If resistance does not drop steadily or resistance values do not match those in the intake air temperature resistance chart, the sensor is faulty.
  2.  
  3. If resistance is within specification, check power and ground circuits.
  4.  

Late Model With Two Terminal Connector

See Figures 3 and 4



Click image to see an enlarged view

Fig. Fig. 3: Intake air temperature sensor schematic-late model



Click image to see an enlarged view

Fig. Fig. 4: Intake Air Temperature To Voltage Chart

  1. Disconnect the sensor electrical harness.
  2.  
  3. Measure voltage between the sensor terminals.
  4.  
  5. Voltage should be high when the engine is cold and steadily drop as the engine warms.
  6.  
  7. If voltage does not drop steadily or voltage values do not match those in the intake air temperature voltage chart, the sensor is faulty.
  8.  
  9. If voltage is within specification, check power and ground circuits.
  10.  

REMOVAL & INSTALLATION



  1. Disconnect the negative battery cable.
  2.  
  3. Drain the engine coolant.
  4.  
  5. Label and disconnect the sensor electrical harness
  6.  
  7. Carefully remove the sensor.
  8.  

To Install:
  1. Coat the sensor threads with Teflon® sealant.
  2.  
  3. Carefully install the sensor and tighten to 14-29 ft. lbs. (20-40 Nm) on all engines except 1.5 (VIN K), 1.8L (VIN M) and 2.0L (VIN F). Tighten 1.5 (VIN K), 1.8L (VIN M) and 2.0L (VIN F) sensors to 11-15 ft. lbs. (15-20 Nm).
  4.  
  5. Connect the sensor electrical harness
  6.  
  7. Fill the engine with coolant.
  8.  
  9. Connect the negative battery cable.
  10.  

 
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