Fuel Injectors, Checking

Check Fuel Injectors

Recommended special tools and equipment
- VAG1526 multimeter or VAG1715 multimeter
- VAG1527 voltage test lamp
- VAG1594 connector test kit
- Wiring diagram

Test requirements





- The respective fuses of fuel injectors (N30 to N33) must be OK.
- Fuel Pump (FP) Relay -J17- must be OK, check.
- Battery voltage must be at least 11.5 volts.
- All electrical consumers like, for example, lights and rear window heating must be switched off.
- Parking brake must be engaged or else daylight driving lights will be switched on.
- For vehicles with automatic transmission, selector lever must be in position -P- or -N-.
- If vehicle is equipped with an A/C system, it must be switched off.
- Ground (GND) connections between engine and chassis must be OK.
- Engine speed (RPM) sensor must be OK, checking. Engine Speed (RPM) Sensor, Checking
- Ignition switched off.

Test sequence
- Remove upper part of intake manifold, Intake manifold, upper part, disassembling and assembling.

NOTE: Seal the intake channels in lower part of intake manifold using a clean rag.

- Disconnect fuel injector connectors.

Resistance values of fuel injectors, checking





- Test resistance of fuel injectors between terminals. Specified value: 14 ... 18 Ohms

NOTE: Resistance value is valid at approx. 20°C. At higher temperatures, resistance value increases.

If specified value is not obtained:
- Replace malfunctioning fuel injector, item 7.

Note the following when installing the fuel injectors:
Replace O-rings on all fuel injectors and wet them slightly with clean motor oil.
Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining clips.
Position fuel distributor on lower part of intake manifold using secured fuel injectors and apply uniform pressure to press it in.
The connectors must audibly engage on valves when attached.

- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

Checking voltage supply

Vehicles with engine code AEG





Connect diode test lamp to connector of fuel injector to be tested terminal 1 and Ground (GND).

Vehicles with engine code AVH, AZG





Connect diode test lamp to connector of fuel injector to be tested terminal 1 and Ground (GND).

Continuation for all vehicles
- Operate starter and test voltage supply for fuel injector. LED must light up.
- Switch ignition off.

If LED does not light up:
- Check wire between 2-pin connector terminal 1 and the Fuel Pump (FP) Relay -J17- for open circuit according to wiring diagram. Wire resistance: max: 1.5 Ohms

Activation and voltage supply, checking

Vehicles with engine code AEG





Connect diode test lamp to the connector terminals of the fuel injector to be checked.

Vehicles with engine code AVH, AZG





Connect diode test lamp to the connector terminals of the fuel injector to be checked.

Continuation for all vehicles
- Operate starter and test activation of fuel injector. LED should flicker.
- Switch ignition off.

If LED does not flicker:
- Connect test box to control module wiring harness, connect test box for wiring test. Test Box, Connecting For Wiring Test

Vehicles with engine code AEG





Check wires between test box and 2-pin connector for open circuit according to wiring diagram. Wire resistance: max: 1.5 Ohms






Also check wires for short circuit to B+ and Ground (GND). Specified value: Infinite Ohms

Vehicles with engine code AVH, AZG





Check wires between test box and 2-pin connector for open circuit according to wiring diagram. Wire resistance: max: 1.5 Ohms






Also check wires for short circuit to B+ and Ground (GND). Specified value: Infinite Ohms

Continuation for all vehicles

If there is no malfunction in wire connection:

- Replace Motronic Engine Control Module (ECM) -J220-.