IAT Sensor for Jeep 4.0 and 2.5

How do you test it to see if they are bad?

To test you need a multi-meter and a hot hair dryer.

Make sure that the engine is cool to ensure accurate testing. Unplug the sensor from the engine harness. Remove it from the engine. Test the sensor leads with your ohm meter while the sensor is still cool, note the current temperature. This is your base reading, so write this number down to refer to it later. Turn on the hair dryer; put the sensor in the pathway of the hot air to simulate hot air coming into the engine. Measure the leads with the ohm meter again. Write down the reading that you get. Find the chart for your engine that shows the temperature to resistance conversion. Compare the readings that you get to make sure the sensor is working correctly.


Below is the Temp to resistance chart for the Jeep YJ & XJ. It may work for other fuel injected Jeeps as well.

Temperature

Resistance (ohms)

C


F


Min


Max


-40

-40

291,490

381,710

-20

-4

85,850

108,390

-10

14

49,250

61,430

0

32

29,330

35,990

10

50

17,990

21,810

20

68

11,370

13,610

25

77

9,120

10,880

30

86

7,370

8,750

40

104

4,900

5,750

50

122

3,330

3,880

60

140

2,310

2,670

70

158

1,630

1,870

80

176

1,170

1,340

90

194

860

970

100

212

640

720

110

230

480

540

120

248

370

410

Chart information comes from the Chrysler service manual for Jeep YJs and XJs.