Passat commanded the intake valve to catch fire.

The fire of Passat intake valve may be caused by carbon deposition or circuit problems.

The carbon deposit in the intake valve prevents the fuel from reaching the cylinder, which affects the effective opening and closing of the intake valve, resulting in lax valve sealing and insufficient cylinder pressure. Long-term carbon deposition will lead to insufficient engine power and spontaneous combustion.

For example, when the power cord is aging and the insulation layer is damaged, resulting in a short circuit, the generated strong current will ignite the insulation layer and then ignite the inside. In the process of long-term frequent use, switch contacts, connectors and other parts will easily heat up due to the increase of resistance, and may eventually cause spontaneous combustion due to local overheating.