Fuel Injectors, Checking

Fuel Injectors, Checking

Special Tools and Equipment
- VAG1526A
- VAG1527B
- VAG1594A
- VAG1598/31







Checking internal resistance







- Remove engine cover (arrows).
- Disconnect harness connector at the fuel injector to be tested.







- Connect multimeter at valve for resistance measurement.
- Specification: 13.5 to 15.5 Ohms

With an engine at operating temperature, the resistance increases by approx. 4 to 6 Ohms.

If specified value is not obtained:
- Replace fuel injector.

Checking voltage supply

Test requirements:
- Fuel Pump (FP) OK, checking. Testing and Inspection
- Fuse for fuel injectors OK
See Electrical Wiring Diagrams, Troubleshooting & Component Locations binder

- Disconnect harness connector at the fuel injector to be tested.







- Connect VAG1527B voltage tester as follows:







- Switch ignition on.
- LED must light up.

If LED does not light up:
- Check wire connection between terminal 1 and fuse for injector valves for open circuit:
- Repair open circuit if necessary.

If LED lights up:

Checking activation

Test requirement:
- Internal resistance of valve OK







- Slide back rubber grommet of fuel injector connector (arrow), but leave connector connected.
- Connect VAG1527B voltage tester between sockets 2 (signal) and 1 (B+).
- Operate starter briefly (engine can also start).
- LED must blink.


NOTE: Voltage testers do not go out completely during low current pick-up between activations by the ECM, but rather continue to glow a little and then get slightly brighter during activation.


If LED does not blink:
- Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. Connecting VAG 1598/31 Test Box







- Check the following wire connections for open circuit and short circuit to Ground (GND) and B+:







- Repair open circuit or short circuit if necessary.

If wire connection is OK:
- Replace Engine Control Module (ECM).