Testing if display approx. - 40°C to - 46°C:

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

-- Using a jumper wire, connect the MAF/IAT sensor -G70/G42- electrical harness connector terminals 4 to 5.

-- Check the value indicated on the scan tool display.

If indication jumps to approx. 140°C:

-- Switch ignition off.

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

If indication remains at approx. -40°C or -46°C:

Checking wiring

If the manufacturers test box is being used, perform the following step.

-- Install the test box.

If the manufacturers test box is not being used, perform the following step.

-- Remove the Motronic Engine Control Module (ECM) -J623-.

-- Disconnect the ECM harness.

-- Using a multimeter, check the MAP/IAT sensor -G70/G42- electrical harness connector terminal 5 to the Motronic Engine Control Module (ECM) -J623- electrical harness connector T94 terminal 60 for an open circuit or a short to voltage, refer to the appropriate SYSTEM WIRING DIAGRAMS information.

Specified values: Circuit continuity; 1.5 Ω max; Circuit voltage = 0 volts when disconnected from ECM (with ignition on).

If the specified value was Not obtained:

-- Check the wiring for an open, high resistance or short circuit to Battery (+)

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If the specified value was obtained: 

-- Using a multimeter, check terminal 4 of the MAF/IAT sensor to engine ground.

Specified value: 1.5 Ω Max

If the specified value was Not obtained: 

-- Check the wiring for an open circuit or high resistance.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the ground circuit: 

-- Replace the Motronic Engine Control Module (ECM) -J623-.