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Old 01-07-2013, 07:34 PM
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Yorgi Yorgi is offline
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Location: Toronto
Join Date: Mar 2005
Posts: 3,650
Mein Auto: '04 M3 / '06 650i Cab
Originally Posted by 645/333 View Post
Hi Yorgi! showing my ignorance hear! the gas cap, is that the same as the petrol tank cap?? And if so what goes wrong with them that causes a code to be raised! Have never experienced this so would be interested as to its effect?? Many thanks Michael
Yes, the petrol cap that you need to remove every time you fill up the car.

There is a rubber seal on this cap that dries out over time and compresses after hundreds of removals, resulting in a less-than-air-tight seal. All modern (OBDII) emission systems pressurize the fuel/petrol tank. Any loss in pressure triggers a check engine light - the assumption being if pressure is leaking from the tank so are fuel vapours into the environment.

Germans are notorious for using low silicon content plastics and rubbers because they are very environmentally conscious. They want the plastics used in cars to eventually break down once the car is retired. The problem is that the plastics start breaking down too soon, within 8 to 10 years, and you start getting all sorts of electrical connection issues and plastic hoses/tanks failing.

The Asians are not afraid to use high silicon plastics and this is one of the reasons they have greater reliability over the Germans.
Straight lines are for fast cars...turns are for fast drivers
'04 M3 - track
'06 650i Cab - daily driver
'02 Highlander - kid hauler
'01 330Ci - winter beater

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