Disconnect the battery negative (-) cable in the cargo compartment. Prior to disconnecting the battery, read the battery disconnection cautions. Remove the cabin microfilter housing, followed by the ignition coil cover and the ignition coil at the corresponding cylinder of the fuel injector service. Maintain a high level of cleanliness when servicing ignition coils, as fuel or oil residue can break down the electrical resistance qualities of silicone used in ignition coil production, leading to coil failure. Remove the fuel line to the corresponding fuel injector by loosening fasteners and removing the fuel line from the rubber mount. If several injectors are being removed, ensure that each injector is reinstalled in its original location. Seal the injector with a cap and plug the fuel rail connections with plugs from the BMW special tool kit. Seal removed high-pressure fuel lines with caps from the same tool kit. Maintain a clean work area when servicing the high-pressure fuel system, as contaminants can cause a malfunction, and seal all fuel system openings with protective caps. Replace high-pressure fuel lines if tightened ten times. Unlock and remove the electrical connector from the injector, then remove the fastener and ground wire. Remove the hold-down element and injectors in the specified order by removing the bolts, lifting off the hold-down bracket, and pulling the injectors straight up. If an injector is stuck in the cylinder head, install the BMW special tool into position, thread screws in by hand a few threads, and screw in the threaded pull-out piece until it is possible to screw threaded sleeves onto the injectors. The threaded pull-out piece has a left-handed thread; tighten the threaded sleeves onto the injectors and then tighten the screws. Set the torque wrench to 5 Nm, fit it along with the special tool on the square head of the special tool, and turn the torque wrench in a clockwise direction until the injector is extracted from the cylinder head. The torque wrench set to 5 Nm corresponds to a maximum tensile force of 2000 N, and the injector must be replaced if the torque wrench indicates that 5 Nm is exceeded. Once the injector is removed, install sealing caps to the fuel line connection and injector tip, which are available from the BMW dealer parts department.