Description And Operation

Courtesy of CHRYSLER GROUP, LLC

The 2-wire Intake Manifold Air Temperature (IAT) sensor is installed in the resonator with the sensor element extending into the air stream.

The IAT sensor is a two-wire Negative Thermal Coefficient (NTC) sensor. Meaning, as inlet air temperatures increase, resistance (voltage) in the sensor decreases. As temperature decreases, resistance (voltage) in the sensor increases.

The IAT sensor provides an input voltage to the Powertrain Control Module (PCM) indicating the density of the air entering the intake manifold based upon intake manifold temperature. At key-on, a 5-volt power circuit is supplied to the sensor from the PCM. The sensor is grounded at the PCM through a low-noise, sensor-return circuit.

The PCM uses this input to calculate the following:

• Injector pulse-width
• Adjustment of spark timing (to help prevent spark knock with high intake manifold air-charge temperatures)

The resistance values of the IAT sensor is the same as for the Engine Coolant Temperature (ECT) sensor.

Comparative table °C/°F/ohm The indicated internal resistance is the nominal resistance
°C	°F	ohm	°C	°F	ohm
-40	-40	48805	50	122	806.9
-30	-22	27414	60	140	575.8
-20	-4	15971	70	158	418.1
-10	14	9620	80	176	308.6
0	32	5975	90	194	231.2
10	50	3816	100	212	175.7
20	68	2502	110	230	135.2
25	77	2044	120	248	105.4
30	86	1679	130	266	83.1
40	104	1152	140	284	66.2