With Generic Scan Tool

Fuel Injectors N30, N31, N32, N33 , checking

The following test procedure is used to diagnose all fuel injectors.

Special tools, testers and auxiliary items required
- Multimeter
- Diode test lamp (12V)
- Wiring diagram

Test requirements
- The Fuel Injectors N30, N31, N32, N33 fuses OK.
- The Engine Speed (RPM) Sensor G28 OK, checking Engine Speed (RPM) Sensor G28, checking. Engine Speed (RPM) Sensor, Checking
- 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. Service and Repair

Start diagnosis






- Disconnect the Fuel Injector electrical harness connectors from Fuel Injectors N30, N31, N32, N33.

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 malfunctioning Fuel Injector.

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 does not flicker:

Checking wiring

If the manufacturers test box is being used. Perform the following step.

- Install the test box Test Box 105 Pin VAG1598/31.

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

- Remove the Motronic Engine Control Module (ECM) J220. Service and Repair






- Using a Multimeter, check the Fuel Injector electrical harness connector terminals to the Motronic Engine Control Module (ECM) J220 electrical harness connector T121 terminals for an open circuit.






Specified value: 1.5 Ohms Max.

If the specification was not obtained:

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

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

- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring:

- Erase the DTC memory. Diagnostic Mode 4: Reset/Erase Diagnostic Data

- Perform a road test to verify repair.

If the DTC does not return:

Repair complete, Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

- End diagnosis.

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

- Replace the MFI Engine Control Module (ECM) J220. Service and Repair

- Assembly is performed in the reverse of the removal.

Final procedures

After the repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory.
2. If necessary, erase the DTC memory.
3. If the DTC memory was erased, generate readiness code.

End diagnosis