Checking the valve injectors (Audi A6 C4)

Table of contents: Resistance check ↓ Checking the supply voltage ↓ Checking the controls ↓

MPI injection system plugs

A - oxygen sensor regulation, idle switch, air mass meter, etc.
B - crankshaft speed meter, trip computer, automatic transmission control
C - intake manifold bypass valves, exhaust gas recirculation, etc.
D - valve injectors, activated carbon system, etc.

Resistance check

1. Pull out the valve injector plug.

2. Connect an ohmmeter between both contacts of the injector valve.

3. The resistance should be between 15 and 17 ohms, otherwise replace the valve injector. Pay attention to the accuracy of the measuring device used, if necessary, check the valve injector again in the workshop before replacing it.

4. Insert the plug and check the next injector.

Checking the supply voltage

Prerequisites for verification:

fuel pump relay and control of this relay are OK;
thermal fuse 3 (red clamp) the ignition system unit in the right footwell is OK.

1. Remove the valve injector plug (see Fig. MPI injection system plugs; shown at the bottom right). Connect the solid-state diode warning lamp to pin 1 of the plug and the motor mass (–).

2. Ask an assistant to turn on the starter for a few seconds, while the indicator lamp should be on.

3. Otherwise, check the integrity of the wire connections going to fuse N13.

Checking the controls

1. Connect the test lamp to contacts 1 and 2 of the plug.

2. Ask an assistant to turn on the starter for a few seconds (the engine may also start in this case). The indicator light should flash.

3. Otherwise, perform an electrical check of the MPI/MPFI injection system. If found, repair the open or short circuit in the wire to the terminal of the MPI/MPFI connector D. See the table.

4. Insert the plug and check the next injector. If the control lamp does not flash when checking all valve injectors, check the supply voltage of the control unit.

5. If the supply voltage is OK, then, as a rule, there is a defect in the MPI/MPFI injection system control unit.