Checking the heating system, removing and installing glow plugs

If you experience difficulties in starting the engine with a starter, you should first check the engine compression. If the compression is too low, the engine will not start at low ambient temperatures. Compression measurement outlined us. 28.

Power check

Connect test pump between cylinder 4 glow plug and vehicle ground.

Turn the ignition key to position II. At the same time, the control lamp should light up. If the control lamp does not light up, use the wiring diagram to check the wiring.

Attention: Do not leave the key in the ignition switch in position II for more than 15 seconds.

Checking glow plugs

Disconnect ground wire (-) battery.

Caution: Disconnecting the battery will erase the contents of the electronic memories, such as engine trouble codes or radio codes. Before switching off, also read the instructions in chapter "Removing and installing the battery".

Remove the plastic caps from the glow plugs.


Unscrew the fastening of the electrical wire to the glow plugs.

Connect an ohmmeter to each glow plug in turn and check whether there is an electrical circuit between the glow plug contact and the cylinder block.

If there is no electrical circuit, the glow plug is defective and should be replaced.

Remove defective spark plug. Screw new glow plug into cylinder head and tighten to 40 Nm.

Attention: Do not exceed the tightening torque, otherwise the glow plug pin will be damaged, which will lead to premature failure of the glow plug. Ensure that no oil or fuel gets on the glow plugs. If you find glow plugs with a burnt pin, follow the instructions below.

Screw the electrical wire to the glow plugs with nuts.

Attention: If no fault is found and the engine does not start well, the glow plugs should be checked during the warm-up phase. To do this, remove the nozzles and observe the heating of the glow plugs through the holes.

Install the plastic caps on the glow plugs.

Connect ground wire (-) battery.

If available, set the clock and enter the radio's anti-theft code.

Glow plugs with burnt pin

Very often, the burning of the glow plug pin is the result of a malfunction of the injector nozzles. This kind of damage cannot be attributed to the shortcomings of candles.



If such a glow plug -arrow- is found in the event of a complaint, it is not sufficient to simply replace it. It is necessary to check the injectors for the pressure of the start of injection and tightness (service station work).