Volkswagen Evap and secondary air system introduction

Volkswagen Evap and secondary air system introduction

Firstly, what is an Air leak and why does it matter?

When your VW has an air leak, you may have a check engine light on and as a result trouble passing NY state inspection.
Basically your engine is a sealed system.  A VW engine is comprised of several compartments; Crank Case, Engine Block, Cylinder head & the Secondary air system to name a few. These compartments operate in different atmospheres, some have a vacuum, whilst others have slight positive pressure but all have valves and pumps that are constantly working. The most common cause of air leaks on VW’s are cracked hose, failed valves and solenoids in the evaporative fuel system or secondary air system.

What does the secondary air system do on my Volkswagen?

The Secondary air system is an environmental component of your Volkswagen, It allows your catalytic converter to function more effeciently which will reduce the concentration of hydrocarbons escaping through your exhaust resulting in cleaner air for everyone!   This is accomplished this by injecting more air into your exhaust system between the downpipe.


What does the Evap System do on my Volkswagen?

Your Evap system is an air circulation system designed to deal with the fumes accumulating in your gas tank.  As you might imagine the air in your gas tank is rich with fuel, which is a hazard since it has a high explosive potential.  The evap system moves this fuel rich air into your engine where is it saftely burned during normal combustion.  When your car is not running these fumes are filtered through the evap canister which is filled with activated charcoal and then vented out.


A few other reasons why your secondary air system is not working properly could be no activation of the secondary air system pump on your VW. This condition can be caused by a bad solenoid, purge valve, or even an air leak.  The secondary air system only operates when certain parameters . If there is an air leak or bad solenoid, quite often the system is not within those parameteres and therefore will not turn on.

If your mechanic is not a VW specialist, air leaks  may be misdiagnosed as bad oxygen sensors or a inefficient catalytic converter which are very expensive.  This is why getting your VW properly diagnosed by a certified technician with experience on Vw's is crucial in avoiding unnecessary repairs and ensuring your Volkwagen gets fixed in a cost effective and timely manner.


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