Testing if display is - 40°C :

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

-- Using a jumper wire, connect the MAF / IAT sensor -G70 / G42- harness connector terminals 1 to 2.

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

-- Switch ignition OFF.

If indication jumps to approx. 140 °C:

-- 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) -J220-. Refer to the Repair Information.

-- Using a multimeter, check the MAF / IAT sensor -G70 / G42- harness connector terminal 2 to the Motronic Engine Control Module (ECM) -J220- electrical harness connector T121 terminal 42 for an open circuit or a short to voltage, refer to the wiring diagram.

-- Using a multimeter, check the MAF / IAT sensor -G70 / G42- harness connector terminal 1 to the Motronic Engine Control Module (ECM) -J220- electrical harness connector T121 terminal 13 for an open, high resistance or a short to voltage, refer to the wiring diagram.

Specified resistance: 1.5 Ω Max.

If the specified value was Not obtained:

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

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

-- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring:

-- Replace the Motronic Engine Control Module (ECM) -J220-. Refer to the Repair Information.