With Manufacturer's Scan Tool

Checking fuel injectors for leaks and quantity injected

Special tools and equipment






- VAG 1348/3 remote control
- VAG 1348/32 adapter
- VAG 1602 calibration tester

Test conditions
Verify that the fuel pressure is correct

Test sequence
- Remove intake manifold upper section

Note: Seal the intake ports in the intake manifold lower section or in cylinder head using a clean cloth.

- Disconnect harness connectors from all fuel injectors.
- Disconnect vacuum hose from fuel pressure regulator.
- Remove fuel rail securing bolts.
- Disconnect air hose for air shrouded fuel injectors from air line
- Lift fuel rail together with fuel injectors off from intake manifold lower section and support it.

Checking for leaks

- Using output Diagnostic Test Mode (DTM), activate cylinder 1 fuel injector -N30- (fuel pump must run).

Note: This procedure allows the fuel pump to run when the engine is not running. The closed throttle position switch must remain closed for this check, otherwise the selected fuel injector will inject 5 times. Check fuel injector for leaks (visual check).

- Check fuel injector for leaks (visual check). Only 1 to 2 drops per minute must emit from each valve when fuel pump is running.

If the fuel loss is greater:
- Turn off ignition.
- Replace faulty fuel injector

Pay attention to the following when installing the fuel injectors:
Replace O-rings on all fuel injectors and lightly moisten with clean engine oil.
Insert fuel injectors vertically and in the correct position into the fuel rail and secure with retaining clips.
Position fuel rail with fuel injectors installed and secured onto intake manifold lower section and press in evenly.

Checking injected quantity

- Insert fuel injector to be checked in a measuring glass of VAG 1602 tester for injected quantity.






- Connect one terminal of fuel injector to be tested to engine Ground (GND) using auxiliary cables from VW1594.
- Connect second fuel injector terminal with auxiliary cable to VAG1348/3 remote control using adapter cable VAG 1348/32.
- Connect alligator clip to battery (B+).

- Using output Diagnostic Test Mode (DTM), activate cylinder 1 fuel injector -N30- [1][2]Output Diagnostic Test Mode (DTM), (Function 03)
Fuel pump must run.

- Operate VAG 1348/3 remote control for 30 seconds.
- Repeat check on other fuel injectors. To do this use new measuring glasses.
- After all fuel injectors have been activated, place measuring containers on a level surface and compare quantity injected.
Specified value: 85-105 ml per fuel injector

If the measured values of one or more fuel injectors are above or below the prescribed specified values:
- Replace faulty fuel injector

Injectors are installed in the reverse order of removal. When installing, pay attention to the following information:
Replace O-rings on all fuel injectors and lightly moisten O-rings with clean engine oil.
Insert fuel injectors vertically and in the correct position into the fuel rail. Secure using retaining clips.
Position fuel rail with fuel injectors installed and secured onto intake manifold lower section and press in evenly.