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Home >> Audi >> 2021 >> S8 >> Repair and Diagnosis >> Transmission >> Transmission Control Systems >> Generic Scan Tool [CWWB,CXYA] (Diagnostic Procedures) >> St Generic Scan Tool >> Diagnosis And Testing >> Diagnostic Procedures >> Low Fuel Pressure Sensor - G410-, Checking

Low Fuel Pressure Sensor - G410-, Checking

General Description 

The low-side fuel pressure is constantly monitored by the Low Fuel Pressure Sensor -G410- and sent to the Engine/Motor Control Module -J623-. If this pressure deviates from the desired pressure, the Engine/Motor Control Module -J623- sends a signal to the Fuel Pump Control Module -J538-. The Fuel Pump Control Module -J538- then sends a PWM signal to the Transfer Fuel Pump -G6- until the desired fuel pressure is achieved.

Special tools and workshop equipment required 

Test requirements 

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.
  • IGNITION: OFF.
  • DISCONNECT: Low Fuel Pressure Sensor -G410- harness connector.
  • IGNITION: ON.
  • CHECK: Low Fuel Pressure Sensor -G410- harness connector terminals 1 to 3 for voltage.
  • IGNITION: OFF.
  • SPECIFIED VALUE: About 5.0 V.
-- Was Value obtained?
-- YES:
  • GO TO: Step 3.
-- NO:
  • GO TO: Step 4.
  • REMOVE: Engine/Motor Control Module - J623-. Refer to appropriate Service Information.
  • CHECK: Low Fuel Pressure Sensor -G410- harness connector terminal 2 to the Engine/Motor Control Module - J623- harness connector T56a / 29 for resistance.
  • SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω).
-- Was Value obtained?
-- YES:
  • REPLACE: Low Fuel Pressure Sensor -G410-. Refer to appropriate Service 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.
  • REMOVE: Engine/Motor Control Module - J623-. Refer to appropriate Service Information.
  • CHECK: Low Fuel Pressure Sensor -G410- harness connector terminal 1 to the Engine/Motor Control Module - J623- harness connector T56a / 21 for resistance.
  • CHECK: Low Fuel Pressure Sensor -G410- harness connector terminal 3 to the Engine/Motor Control Module - J623- harness connector T56a / 25 for resistance.
  • SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω).
-- Were Values 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.
  • Final Procedure 
  • Perform a road test to verify repair.
-- Does the original DTC return?
-- YES:
  • CHECK: Engine/Motor Control Module -J623- harness connector for any damaged, pushed-out pins.
  • REPAIR: As necessary.
  • If all electrical connections are OK:
  • REPLACE: Engine/Motor Control Module -J623-. Refer to appropriate Service 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.