1.Set the vehicle to the continuous idling mode.

caution Beware that, even if the injector to be checked is not operating, the operation sound of other injectors may be heard.
Use a stethoscope to listen to the operation sound (ticks) from the injectors.
3.Verify that the operation sound increases with the higher engine speed.
note If the operating sound cannot be heard, inspect the injector actuation circuit.


1.Disconnect the injector connector.
2.Measure the resistance between terminals.
Standard value: 10.5 - 13.5 Ω (at 20°C)
3.If the resistance is deviates from the standard value, replace the injector.


1.Release the residual pressure in the fuel pipe line to prevent the fuel from running out (Refer to ).
caution Cover the hose connection with rags to prevent splash of fuel that could be caused by some residual pressure in the fuel pipe line.
Remove the fuel high-pressure hose at the delivery pipe.
3.Remove the injector.

4.Assemble the special tool called injector test set (MB992076) as shown in the figure according to the following procedure.

  1. Disconnect the injector mounting hose.
  2. Remove the adapter for mounting injector and attach the special tool Injector test nipple (MB992088) instead.
  3. After attaching the injector on the special tool Injector test nipple (MB992088), secure it with the special tool injector holder (MB992184).
5.Mount the injector test set (MB992076) prepared with the special tool hose adapter (MB992001) onto the fuel high-pressure hose.
6.Connect the M.U.T.-III to the diagnosis connector.
7.Operate the electric motor switch without depressing the brake pedal and turn ON the power supply mode of electric motor switch.
8.Select "Item No. 9" of the M.U.T.-III actuator test to drive the fuel pump.

9.Connect the special tool Injector test harness (MB991607) between the injector and auxiliary battery to drive the injector.
10.Check each injector for spray conditions. The condition can be considered satisfactory unless it is extremely poor.
11.Stop the actuation of the injector, and check for leakage from the injector nozzle.
Standard value: 1 drop or less per minute
12.After Turning off the power supply mode of the electric motor switch, remove the M.U.T.-III.
13.Actuate the injector until it does not spray fuel any longer, then drain the fuel inside the special tool.
14.Remove the special tool.
15.When the spray condition is extremely poor or any fuel leaks from the injector nozzle, replace the injector.
16.Replace the injector and fuel high-pressure hose in the original places.