Evaporative Emissions System: Service Precautions

Safety Precautions


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

• Before opening the fuel system, lay a clean cloth around the connection point and carefully loosen it, which lowers the pressure.

• Vehicles with a FSI or TFSI engine: The engine side fuel system, after the high pressure pump, is under extremely high pressure. When working on engine or fuel injection system, pressure must be relieved to residual pressure before opening high pressure components.

Risk of escaping fuel.

• To prevent the fuel pump from running when the driver door is opened, the fuel pump fuse must be removed for safety reasons before opening the fuel system if the battery is not disconnected or the fuel pump delivery unit electrical connector is not disconnected. Fuse assignment.

Carry out the following measures before starting work on the fuel supply:


Risk of explosion due to cell phones.

• Keep cell phones out of reach in the work space area.


Risk of destroying electrical components when battery is disconnected.

• Observe measures when disconnecting battery.

• Only disconnect battery with ignition switched off.

• Disconnect battery.

• Open fuel filler flap briefly and then close again.

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 removing and installing components from a filled or partially filled fuel tank:

• The fuel tank may only be partially full. How much fuel can remain in the fuel tank may be read in the respective work description. Refer to => [ Fuel Tank, Draining, FWD ] Fuel Tank, Draining, FWD, or => [ Fuel Tank, Draining, AWD ] Fuel Tank, Draining, AWD.

• Before starting work, switch on exhaust extraction system and place an extraction hose close to the installation opening of fuel tank to extract escaping fuel fumes. If no exhaust extraction system is available, a radial fan (as long as motor is not in air flow) with a displacement greater than 15 m3/h can be used.

• Prevent fuel from contacting skin! Wear fuel-resistant gloves!

Note the following when removing and installing the fuel tank:

• Fuel tank must be empty for weight reasons. Refer to => [ Fuel Tank, Draining, FWD ] Fuel Tank, Draining, FWD, or => [ Fuel Tank, Draining, AWD ] Fuel Tank, Draining, AWD.