IAT In MAF Sensor, Checking: Notes

NOTE:

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

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

-- Observe safety precautions. Refer to SAFETY PRECAUTIONS

-- Observe Clean Working Conditions. Refer to CLEAN WORKING CONDITIONS

-- 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)		actual ambient air temperature

If the specified value was obtained:

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

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 3 to 4 for resistance.

Use the chart below for the specified values:

Specified values:

IAT Temperature vs Resistance
Temp (C)	min. value ohms	max. value ohms
- 35	28840	33978
- 25	17680	20530
- 15	10940	12534
- 5	6897	7804
0	5535	6226
5	4443	4970
15	2923	3235
25	1978	2167
35	1369	1486
45	965	1039
55	692	738
65	503	533
75	372	392

If the specified values were Not obtained:

-- Replace the MAF / IAT sensor -G70 / G42- Refer to the Repair Information.

If the specified values are obtained, continue the test according to the following table:

Indicated reading	Cause	Test
approx. - 40 °C to -46 °C	Open circuit or short circuit to (B+)	TESTING IF DISPLAY APPROX. - 40° C TO - 46° C
approx. 140 °C	Short circuit to Ground	TESTING IF DISPLAY APPROX. 140° C