Fuel Quality Sensor -G446-, 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 Fuel Quality Sensor -G446- uses two measuring electrodes immersed in the fuel flow in the fuel line upstream of the fuel injectors. The fuel becomes an electrical element (dielectric) of the sensors electrical circuit. The resistance of the fuel changes depending on ethanol content. These electrical variables are measured, and reported to the Engine Control Module -J623-. The Engine Control Module -J623- then calculates the necessary mixture and ignition corrections applicable to a particular set of engine operating characteristics.

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	IGNITION: OFF. DISCONNECT: Fuel Quality Sensor -G446- harness connector. IGNITION: ON. CHECK: Fuel Quality Sensor -G446- harness connector terminal 3 to 2 and ground for voltage. SPECIFIED VALUE: Battery voltage. IGNITION: OFF. -- Was Value obtained?	-- YES: GO TO: Step 3 -- NO: GO TO: Step 4
3	REMOVE: Engine Control Module - J623-. Refer to appropriate repair information. CHECK: Fuel Quality Sensor -G446- harness connector terminal 1 to the Engine Control Module - J623- harness connector T60 / 53 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Was Value obtained?	-- YES: REPLACE: Fuel Quality Sensor -G446-. Refer to appropriate repair information. 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
4	REMOVE: Engine Control Module - J623-. Refer to appropriate repair information. REMOVE: Fuse that powers the Fuel Quality Sensor -G446-. Refer to appropriate SYSTEM WIRING DIAGRAM. CHECK: Fuel Quality Sensor -G446- harness connector terminal 3 to the output side of the appropriate fuse for resistance. Refer to appropriate SYSTEM WIRING DIAGRAM. CHECK: Fuel Quality Sensor -G446- harness connector terminal 2 to the Engine Control Module - J623- harness connector T60 / 59 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω) -- Were Values obtained?	-- YES: REPLACE: Fuel Quality Sensor -G446-. Refer to appropriate repair information. 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.