Fuel Tank Leak Detection Control Module -J909 - / Fuel Tank Pressure Sensor -G400-, 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 system can test the evaporative system integrity by using natural vacuum after the engine is shut off. The Engine Control Module -J623- monitors the ability of the system to maintain vacuum through signals sent from the Fuel Tank Pressure Sensor -G400- / Fuel Tank Leak Detection Control Module -J909-. If the vacuum remains for a specified period of time, then there are no evaporative leaks, and a PASS is reported by the Engine Control Module -J623-. If there is a leak, the system either will not achieve a vacuum, or a vacuum cannot be maintained. Usually a fault can only be detected after a cold start.

Special tools and workshop equipment required

Multimeter
Wiring Diagram
Scan Tool
Hand Vacuum pump
Evap Smoke Tester

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 Manual 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	REMOVE: Evaporative Canister. Refer to appropriate repair information. Plug or Cap off the Fuel Tank Pressure Sensor -G400- hose going to the vent filter. CONNECT: Hand vacuum pump to the Fuel Tank Pressure Sensor -G400- and apply 0.700 bar and see if the vacuum holds. -- Did the vacuum hold?	-- YES: GO TO: Step 3 -- NO: REPLACE: Fuel Tank Pressure Sensor -G400-. Refer to appropriate repair information. GO TO: Step 6
3	DISCONNECT: Fuel Tank Pressure Sensor -G400- harness connector CHECK: Fuel Tank Pressure Sensor -G400- component connector terminals 1 to 3 for resistance. SPECIFIED VALUE: 18 - 30 Ω (± 5.0 Ω @ approx. 20° C) -- Was Value obtained?	-- YES: GO TO: Step 4 -- NO: REPLACE: Fuel Tank Pressure Sensor -G400-. Refer to appropriate repair information. GO TO: Step 6
4	IGNITION: ON. CHECK: Fuel Tank Leak Detection Control Module -J909 - harness connector terminal 1 to ground for voltage. IGNITION: OFF. SPECIFIED VALUE: Battery voltage. -- 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 6
5	REMOVE: Engine Control Module - J623-. Refer to appropriate repair information. CHECK: Fuel Tank Leak Detection Control Module -J909 - harness connector terminal 2 to the Engine Control Module - J623- harness connector T94 / 54 for resistance. CHECK: Fuel Tank Leak Detection Control Module -J909 - harness connector terminal 3 to the Engine Control Module - J623- harness connector T94 / 52 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: REPLACE: Fuel Tank Leak Detection Control Module -J909-. Refer to appropriate repair information. GO TO: Step 6 -- 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 6
6	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.