Air Filter Hose: Replacement & Installation Guide

Hello.

I have a Passat TDI, manufactured in 1995. I'm now planning to install an open air filter. While I was working near the air intake manifold, I found a small hose. What is this hose for, and what should I do with it? It doesn't fit onto the open air filter.

Thank you in advance.

Hello,

"The thing about the open air filter is a bit too advanced for me; I don't understand why anyone would want to install something like that, but whatever."
The hose you're referring to connects to the top of the air filter housing and is a black, fabric-covered hose, approximately 1 cm in diameter.
If you absolutely want to install an open filter, to relieve the vacuum system, insert a fuel filter or similar into the hose to prevent dirt from being sucked into the vacuum system.

Best regards, Rainer.

Hi.

. . . can sometimes be more educational than anything else.
Okay, so please follow the hose and describe again, as precisely as possible, where it leads from and to.
Then I can probably help you.

But with your description, I can't really pinpoint anything specific, except for a vague guess --> AGR solenoid valve.

'Yes, that's the hose with the fabric covering that connects to the top of the air filter housing.'

Thank you for the quick responses.

I had already installed the air filter for testing purposes, and I left the hose open. Since then, my power box hasn't been working. Could it be that I'm running in a limp mode?

Hello,

The emergency mode feels like it's producing a maximum of 60-70 horsepower, and you would definitely notice that.

Best regards, Rainer.

Hi,

Most power boxes are connected to the mass airflow sensor (MAF).
Check if any cable from the power box is dangling loose somewhere. Since you installed the open filter, the air filter box was probably removed. Maybe you accidentally cut the cable, forgot to reconnect it, or something like that.

I haven't had an open air filter before, but I was once offered one, and I should have closed that hose, as I said, to prevent any dirt from getting in.
Unfortunately, I don't know exactly what it's used for.

Greetings,
Thomas.