IAT Sensor, Checking: Notes

NOTE:

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

If the specified value was Not obtained:

Checking internal resistance

-- Disconnect the IAT sensor - G42- electrical harness connector.

-- Using a multimeter, check the IAT sensor - 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 was Not obtained:

-- Replace the IAT sensor - G42- Refer to the appropriate Service Information.

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

Indicated reading	Cause	Test
Fixed at approx. - 40 °C to -46 °C	Open circuit or short circuit to (B+)	Testing if display approx. - 40° C to - 46° C:
Fixed at approx. 140 °C	Short circuit to Ground (GND)	Testing if display approx. 140° C: