Generic Scan Tool

Fuel Injectors, Checking

The following test procedure is used to diagnose Fuel Injectors (N30, N31, N32, N33, N83, N84).

Special tools, testers and auxiliary items required

• Multimeter.

• Diode test lamp (12V).

• Wiring diagram.

Test requirements

• Fuel Injector Fuse OK.

• Motronic Engine Control Module (ECM) (J220) Fuse OK.

• Motronic Engine Control Module (ECM) Power Supply Relay (J271) OK.

• Battery voltage at least 12.5 volts.

• All electrical consumers such as, lights and rear window defroster, switched off.

• Vehicles with automatic transmission, shift selector lever into position " P" or "N".

• A/C switched off.

• Ground (GND) connections between engine/transmission/chassis OK.

• Ignition switched off.

- Observe Safety Precautions.

- Observe rules for cleanliness.

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check.

Start diagnosis

- Remove the Fuel Injector electrical harness retaining screws - arrows -.





- Remove the Fuel Injector electrical harness- arrows - from the fuel rail.





- Disconnect the Fuel Injector electrical harness connectors - 1,2,3,4,5,6 - from the Fuel Injectors.

Checking internal resistance

- Using a multimeter, check the Fuel Injector electrical terminals 1 to 2 for resistance.





Specified value: 12.0 to 20.0 ohms (at approx. 20° C)

If the specified value was not obtained:

- Replace the faulty Fuel Injector. Refer to Fuel Injection and Ignition Repair Information

If the specified value was obtained:

Checking activation

- Connect a diode test lamp (12V) to the electrical harness connector terminals 1 and 2 of the Fuel Injector to be tested.





- Operate the starter and test the activation of the Fuel Injector.

LED should flicker.

- Switch the ignition off.

If LED flickers:

- Replace the faulty Fuel Injector. Refer to Fuel Injection and Ignition Repair Information

If LED does not flicker:

Checking voltage

- Using a Multimeter, check the Fuel Injector electrical harness connector terminal 1 to ground (GND) for voltage.

- Operate the starter.

Specified value: Battery voltage.

If the specification is not obtained:

- Check the wiring from the Fuel Injector electrical harness connector terminal 1 to the Battery (+) 1 in the interior wiring harness for a short circuit to Ground (GND), or an open circuit.





- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

Checking wiring

If the manufacturers test box is being used, perform the following step.

- Install the test box (VAG1598/31). Refer to Fuel Injection and Ignition Repair Information

If the manufacturers test box is not being used, perform the following step.

- Remove the Motronic Engine Control Module (ECM) ( J220). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Using a Multimeter, check the Fuel Injector electrical harness connector terminals to the Motronic Engine Control Module (ECM) (J220) electrical harness connector terminals for resistance.









Specified value: 1.5 ohms Max.

If the specification is not obtained:

- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring:

- Erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

- Perform a road test to verify repair.

If the DTC does not return:

Repair complete, Generate readiness code. Refer to => [ Readiness Code ] Readiness Code.

- End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:

- Replace the Motronic Engine Control Module (ECM) (J220). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Assembly is performed in the reverse of the removal.

Final procedures

After repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Readiness Code.

End of diagnosis