Safety Precautions

Safety Precautions

Note the following when working on the fuel system:


There is a risk of injury because the fuel is under very high pressure.

• Reduce the fuel pressure down to residual pressure before opening high pressure area of the fuel injection system.

• To reduce remaining residual pressure, place a clean cloth around the connector and carefully loosen connector.

- Procedures before opening high pressure fuel injection system.

To prevent personal injury and damage to the injection and ignition system, observe the following:

• The ignition must be switched off before connecting or disconnecting injection and ignition system wiring or tester cables.

• Only clean engine with ignition switched off.

• If electrical connectors were disconnected and the engine was started, then malfunctions have been stored in the engine control modules. "Generate readiness code" in "Guided Functions" => Vehicle Diagnosis Tester.


Danger of causing damage to electrical components when disconnecting the battery.

• Complete the steps for disconnecting the battery.

• Turn off the ignition and disconnect the battery.

- Disconnect the battery.

Before Opening High Pressure Fuel Injection System


• The injection system is separated into a high-pressure section (maximum approximately 120 bar) and a low-pressure section (approximately 6 bar).

• Before opening high pressure area, fuel pressure must be reduced to a residual pressure of approximately 6 bar.

Note the following when working on the cooling system:


Risk of scalding due to hot steam and hot coolant.

• The cooling system is under pressure when the engine is warm.

• Cover the coolant reservoir cap with a cloth and then open it slowly to release the pressure in the system.


The vehicle could overheat if the cap is installed incorrectly.

• The cap must engage noticeably when sealing.

If it is necessary to use testing and measuring devices on road tests, observe the following:


Distraction and improperly secured test equipment can lead to accidents.

There is a risk that the passenger airbag could deploy in a collision.

• Operating testing and measuring equipment while driving creates a distraction.

• There is an increased risk of injury due to unsecured testing and measuring equipment.

• Always secure testers on the rear seat with a strap and have a second person on the rear seat operate them.

Note the following when working on the exhaust system:


Danger of damaging the decoupling element.

• Decoupling element must not be bent more than 10°.

• Do not load decoupling element on cable.

• Do not damage wire mesh at decoupling element.