Spark plugs (Audi A6 C5)

The spark plug consists of a central electrode, an insulator with a housing and a ground electrode. The spark that ignites the fuel-air mixture jumps between the central electrode and the ground electrode. It is necessary that only the prescribed type of spark plugs be installed on the engine, taking into account the heat rating index. The heat rating index indicates the degree of maximum permissible thermal load of one spark plug. The lower the heat rating index, the higher this permissible thermal load. Such a spark plug dissipates heat better, which prevents dangerous pre-ignition. However, the disadvantage of a spark plug with a high permissible thermal load is that its self-cleaning temperature is also high. Therefore, it becomes covered with soot faster, especially when the engine often does not warm up to normal operating temperatures while driving (driving in urban conditions, short-distance travel in winter).

The heat rating is specified by the vehicle manufacturer. There are spark plugs with one or more poles, with different thread lengths and different thread diameters. Therefore, when replacing spark plugs, it is important to use only those spark plugs that are specified by the vehicle manufacturer.

The average service life of spark plugs varies greatly. The material from which the electrodes are made plays an important role. Chrome-nickel alloy has high thermal conductivity and corrosion resistance; silver has the best thermal conductivity among metals, and platinum electrodes have high anti-corrosion qualities and are resistant to fading. The service life of spark plugs ranges from 20,000 km to 100,000 km, depending on the electrode material and design used (single pole or multi pole) spark plugs.



There are two types of seals when installed in the cylinder head: flat seat and elastic (steel or copper-asbestos) gasket or with a conical seat without a gasket. When the dimensions of the units are limited, spark plugs with a flat seal and a reduced size of the hexagon under the key are often used, or they install spark plugs with a conical seal, which, due to the compact design, have reduced external dimensions.

When installing a new spark plug, it is necessary to check what kind of seal is provided in the cylinder head, the diameter and length of the threaded part.

Spark plugs installed in A6 car engines must have three side (ground) electrodes.

Spark plugs must be replaced after 60,000 km of vehicle mileage.