The spark plug is the most important element of the ignition system for internal combustion engines (ICE) with forced ignition of the working mixture. This device is designed to ignite the working mixture in the engine cylinder in order to obtain thermal energy, which is subsequently converted into mechanical work by means of the crank mechanism.

1. 900 II
2. 900 II Convertible
3. 850 Estate (855)
4. 850 Rural (855)
5. 900 I Combi Coupe
6. 900 � Combi Coupe
7. MEGANE CC (EZ0/1_)
8. 850 (854)
9. S70 (874)
10. S70 Saloon (874)
11. V70 I (875, 876)
12. V70 � (875, 876)
13. 900 I (AC4, AM4)
14. 900 � (AC4, AM4)
15. 900 I Convertible
16. 900 � Convertible
17. C70 I Coupe (872)
18. S40 I (644)
19. S40 I Saloon (644)
20. V40 Estate (645)
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The principle of the spark plugs work

BOSCH brand Spark Plug are the most widely used in modern automotive internal combustion engines. Ignition of the working mixture in such devices is carried out by an electric arc discharge in the form of a spark between the electrodes of a candle, which occurs when a powerful electric pulse with a voltage of several thousand or even tens of thousands of volts is applied to the electrodes. A thin layer of air in the spark gap cannot withstand the colossal voltage between the electrodes, and a kind of mini-lightning breaks through it, setting fire to the mixture.

The impulse is applied to the electrodes of the plug at a strictly defined point in time - when it is necessary to ignite the prepared working mixture in the cylinder.