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HOMESERVICE MANUALSVOLKSWAGEN2012JETTA TDI, 4D SEDAN, STANDARD TRANSREPAIR AND DIAGNOSISTRANSMISSIONAUTOMATIC TRANS2.0L - GENERIC SCAN TOOL - ENGINE CODE: CJAA (SEDAN)ST GENERIC SCAN TOOLDIAGNOSIS AND TESTINGDIAGNOSTIC PROCEDURESENGINE SPEED SENSOR - G28-, CHECKING
2012 Volkswagen Jetta TDI, 4D Sedan, Standard Trans

Engine Speed Sensor - G28-, CHECKING

2012 Volkswagen Jetta TDI, 4D Sedan, Standard TransSECTION Engine Speed Sensor - G28-, CHECKING

Function 

The Engine Speed Sensor -G28- detects rpm and reference marks from a toothed wheel on the crankshaft. Without an engine speed signal, the engine will not start. If the engine speed signal fails while the engine is running, the engine will stop immediately.

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 .

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 or CRANK: Engine.
  • CHECK: Engine rpm.
  • SPECIFIED VALUE: Cranking or Idle rpm.
  • IGNITION: OFF.
-- Was Value obtained?		 -- YES:
  • GO TO Step 3.
-- NO:
  • GO TO Step 4.
3 
  • 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 7.
4 
  • DISCONNECT: Engine Speed Sensor -G28- harness connector.
  • IGNITION: ON.
  • CHECK: Engine Speed Sensor -G28- harness connector terminals 1 to 3 for voltage.
  • SPECIFIED VALUE: About 5.0 V.
  • IGNITION: OFF.
-- Was Value obtained?		 -- YES:
  • GO TO Step 5.
-- NO:
  • GO TO Step 6.
5 
  • REMOVE: Engine Control Module - J623-.
  • CHECK: Engine Speed Sensor -G28- harness connector terminal 2 to the Engine Control Module - J623- harness connector T60 / 52 for resistance.
  • SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω).
-- Was Value obtained?		 -- YES:
  • REMOVE: Engine Speed Sensor -G28-.
  • CHECK: Engine Speed Sensor -G28- wheel for proper seating, damage and/or run - out.
  • Sensor wheel OK.
  • REPLACE: Engine Speed Sensor -G28-.
  • GO TO: Step 7.
-- NO:
  • 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 7.
6 
  • REMOVE: Engine Control Module - J623-.
  • CHECK: Engine Speed Sensor -G28- harness connector terminals 1 to the Engine Control Module - J623- harness connector T60 / 25 for resistance.
  • CHECK: Engine Speed Sensor -G28- harness connector terminals 3 to the Engine Control Module - J623- harness connector T60 / 53 for resistance.
  • SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω).
-- Were Values obtained?		 -- YES:
  • REPLACE: Engine Control Module -J623-.
  • GO TO: Step 7.
-- NO:
  • 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 7.
7 
  • Final Procedure 
  • Perform a road test to verify repair.
  • Do any DTC's return:
 -- YES: -- NO:
  • Repair is complete. Generate readiness code. Refer to READINESS CODE .
  • Return vehicle to Customer.
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.