Intake Air Temperature Sensor, Checking: Notes

NOTE:

The Mass Air Flow sensor and the Intake Air Temperature sensor are combined as a unit.

Use only gold-plated terminals when servicing terminals in the electrical harness connector of the MAF / IAT sensor -G70 / G42-.

Special tools and workshop equipment required

Test procedure

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK

Start diagnosis

-- Connect the scan tool.

-- Engine must be at Room Temperature.

-- Switch the ignition ON.

-- Using the scan tool, check the intake air temperature:

Diagnostic text		Specified value
Intake Air Temperature (IAT)		approx. ambient air temperature

If the specified value was obtained:

-- Fault is intermittent. Check for proper connection, damaged wiring or loose terminals.

-- Switch the ignition OFF.

If the specified value was Not obtained:

Checking internal resistance

-- Disconnect the MAF / IAT sensor -G70 / G42- electrical harness connector.

-- Using a multimeter, check the MAF / IAT sensor -G70 / G42- terminals 1 to 2 for resistance.

Use the chart below for the specified values:

Specified values:

IAT Temperature vs Resistance
Temp (C)	min. value ohms	max value ohms
- 40	31811	37560
- 35	22941	26863
- 25	12415	14289
- 15	6958	7880
- 5	4036	4495
0	3120	3442
5	2422	2655
15	1519	1623
25	968	1031
35	629	676
45	419	455
55	286	314
65	195	217
75	136	155

If the specified value in the chart was Not obtained:

-- Replace the MAF / IAT sensor -G70 / G42-.

If the specified value was obtained:

-- Continue the test according to the following table:

Indicated	Cause	Test
Between -39 to 139 °C	Component or wiring	Checking Component and wiring
-40 to -46 °C	Open circuit or short circuit to (B+)	Testing if display is - 40°C :
140 °C	Short circuit to Ground	Testing if display near 140°C: