filter inside the air filter cover

My German variant 2007 Prius does not have a filter built into the air filter housing cover. Assuming that the regular replacement filter is a normal full filter, then there should be no danger of damage if the cover-filter is removed.

At the moment I have no access to my manuals, but I offer the following guess: The cover filter is for the US variant in order to fulfill the requirements for Partial Zero Emmisions Vehicles (PZEV). It is possibly an activated carbon filter for capturing any traces of gasoline fumes which may drift out of the intake manifold while the gasoline engine is not running.

If this is the case, then it may not pass a smog check if the filter is removed.

Perhaps you are mistaking activated charcoal for dirt?

 

The “dirty filter” is a charcoal filter whose purpose is to trap HC rising up from the intake manifold. I suggest you leave it alone.

 

PC rule no. 2: Always heed Patrick Wong's advice.

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I find it remarkable and admirable to what extent Toyota went to honestly make the US Prius truly an extremely low emissions car. In addition to the air intake VOC filter dicussed above, there is the fuel tank bladder, the heat storage tank, the multi-stage warm up cycle, the preheated exhaust sensors, etc..

Especially after those despicable sleazy swindlers at VW resorted to deception and mockery to steal sales from Prius, I appreciate it even more. VW still owes Toyota a very, very big public apology.

 

If it were up to me, owners of the "clean" diesel models would have 30 days to drive to a VW dealership of their choice, and trade in for a NEW non-diesel of their choice at VWs expense. These models would be returned to Germany at VWs expense, as there was no legitimate fix available, and were NEVER to be sold in the US due to inability to meet emission standards w/o deception. The massive fines would still come later. Money earned (salary, stock options, 401k, pension) during the deceptive period would be CLAWED BACK. Anyone who had knowledge and did NOT speak-up would be resocialized in prison. Justice served.

A much better deterrent against corporate malfeasance, unlike the sub-prime fiasco, where no one got the privilege of socialization in the prison system.