Engine Performance
Work Example 5

WorkKey Level: 4
NATEF Automotive Tasks: VIII.B.3, VIII.B.4, VIII.B.6

The resistance of a coolant temperature sensor reads 1025 OHMS.  Looking at the chart below, what is the approximate temperature of the coolant in Fahrenheit? 

 Coolant Temperature Sensor
Temperature to Resistance Values (Approximate)

ºF	ºC	Ohms
210	100	185
160	70	450
100	38	1,600
70	20	3,400
40	–4	7,500
20	–7	13,500
0	–18	25,000
–40	–40	100,700

 

 

 

 

 

 

 

Solution:

Look at the chart. In the Ohms column, the value 1025 is exactly halfway between 450 and 1600. The readings in Fahrenheit are 160 and 100. Since it is halfway between the two values, the students should arrive at an answer of approximately 130^°F.
x = (160° + 100°)/2 = 260/2 = 130°F