S5 Quattro Coupe V8-4.2L (CAUA) (2009)
Specified value: battery voltage.
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Switch the ignition off.
If specified value was not obtained:
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Check the Mass Air Flow (MAF) Sensor (G70)/Intake Air Temperature (IAT) Sensor (G42) electrical harness connector terminal 2 to the Engine
Component Power Supply Relay (J757) socket 2/87 for an open circuit or a short circuit to Ground (GND).
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Check the electrical harness connector for damage, corrosion, loose or broken terminals.
If no malfunction is detected in the wiring and the voltage supply was OK:
Checking electrical circuit
If the manufacturers test box is being used, perform the following step.
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Install the test box.
If the manufacturers test box is not being used, perform the following step.
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Remove the Motronic Engine Control Module (ECM) (J623). Refer to => [ Engine Control Module, Replacing ] See: Engine Control
Module/Service and Repair/Engine Control Module, Replacing.
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Using a multimeter, check the Mass Air Flow (MAF) Sensor (G70)/Intake Air Temperature (IAT) Sensor (G42) electrical harness connector
terminals to the Motronic Engine Control Module (ECM) (J623) electrical harness connector T94 terminals for resistance.