If headlamps or other vehicle lamps are fogged up on the inside, car drivers usually consider this to be a defect. However, in some cases this is a physical phenomenon. This page explains how this can come about. You will also find out what to do if water collects in the headlamp or other vehicle lamps. There is also a step-by-step guide for replacing faulty lamps, which provides a number of practical tips.

With the above-mentioned vehicle, various failures/malfunctions (cruise control, gear selector) may occur in conjunction with the multifunction steering wheel. The error message "cruise control failed" may then appear in the instrument cluster.

Upon identifying a steady coolant loss in the above-mentioned vehicles, check all coolant hose connections and the radiators for leaks. We recommend pressurising the cooling system with a suitable tool according to the manufacturer's specifications.

If the headlamps on this vehicle are permanently on and / or it is not possible to switch between low and high beam, the cause could be a faulty multifunction switch. In addition, the error may be stored in the control unit.

Injection valves provide each cylinder with the required fuel and simultaneously atomise the fuel so that it can burn most effectively in the combustion chamber. Scroll through this page and find out how injection valves work and potential fault symptoms. You will also find useful tips for performing troubleshooting work on injection valves with the engine running and switched off.

If the above-mentioned defect is detected, it may be related to a problem with the keyless central locking system. Because of water ingress and corrosion affecting the door handle switches, the receiver detects an opening request and sends this signal to the body control unit.

On the above-mentioned vehicles, bulbs for halogen headlamps can be replaced as follows:

• Switch off the ignition
• Disconnect the headlamp from the power supply by unplugging the electrical supply line

Vehicles with an adjustable or sliding sunroof are affected. When the sunroof is opened, water can penetrate into the vehicle interior.

Tyre pressure is an essential safety factor of a vehicle. The most common tire damage can be traced back to a gradual pressure loss. This is often noticed by the driver of the vehicle when it is too late. Insufficient tyre pressure causes increased fuel consumption and poor driving characteristics.

The following symptoms may occur in the above-mentioned vehicles due to faulty engine control unit software:

• Engine cuts out after cold start
• Engine cuts out when disengaging the clutch in coasting mode

The following symptoms may occur in the above-mentioned vehicles due to faulty ESP/ABS control unit software.

Sufficient coolant liquid amount is prerequisite for flawless operating of engine. On this page, we show you the functions of the coolant, the ideal mixing ratio and how to determine the antifreeze content in coolant.