Mass Airflow Sensor -G70-, CHECKING

WARNING: This page is about a different car, the 2015 Audi A4 Quattro, 2014 Audi A4 Quattro, and 2013 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

General Description

The signal from the Mass Airflow Sensor is used in the Engine Control Module -J623- to calculate the volumetric efficiency. Based on the volumetric efficiency, and taking into consideration the lambda value and ignition timing, the Engine Control Module -J623- calculates the engine torque.

Special tools and workshop equipment required

Multimeter
Wiring Diagram
Scan Tool

Test requirements

Fuses OK.
Battery voltage OK.
Switch OFF all electrical and electronic accessories.
Vehicles with Auto. Transmission, ensure Selector Lever position is in "P".
Vehicles with Man. Transmission, ensure Shifter Lever position is in "N" with Parking Brake applied.
Coolant Temperature: ≥ 80° C.
Observe all safety precautions: SAFETY PRECAUTIONS .
View clean working conditions: CLEAN WORKING CONDITIONS .
For Hybrid vehicles refer to: HIGH VOLTAGE SYSTEM GENERAL WARNINGS .

Test Procedure

Step	Procedure	Result / Action to Take
1	PERFORM: Preliminary Check to verify the customers complaint. Refer to PRELIMINARY CHECK . -- Was Complaint verified?	-- YES: GO TO: Step 2 -- NO: GATHER more information from customer about the complaint.
2	CONNECT: Scan tool. START: Engine and let Idle. CHECK: The air flow quantity of the Mass Air Flow Sensor -G70-. SPECIFIED VALUE: About 2 to 5 g/s. IGNITION: OFF. -- Was Value obtained?	-- YES: Condition may be intermittent. PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 5 -- NO: GO TO: Step 3
3	DISCONNECT: Mass Airflow Sensor -G70- harness connector. IGNITION: ON. CHECK: Mass Airflow Sensor -G70- harness connector terminal 3 to ground for voltage. SPECIFIED VALUE: Battery voltage. IGNITION: OFF. -- Was Value obtained?	-- YES: GO TO: Step 4 -- NO: PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 5
4	REMOVE: Engine Control Module - J623-. Refer to appropriate repair information. CHECK: Mass Airflow Sensor -G70- harness connector terminal 1 to the Engine Control Module - J623- harness connector T94 / 23 for resistance. CHECK: Mass Airflow Sensor -G70- harness connector terminal 2 to the Engine Control Module - J623- harness connector T94 / 65 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Was Value obtained?	-- YES: GO TO: Step 5 -- NO: PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 5
5	Final Procedure Perform a road test to verify repair. -- Does the original DTC return?	-- YES: CHECK: Engine Control Module -J623- harness connector for any damaged, pushed-out pins. REPAIR: As necessary. If all electrical connections are OK: REPLACE: Engine Control Module -J623-. Refer to appropriate repair information. Clear the DTC's. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY . Repair is complete. Generate Readiness Code. Refer to READINESS CODE . Return vehicle to Customer. -- NO: Perform the diagnostic procedure for any DTC's. If no DTC's return the repair is complete. Return vehicle to customer.