Evaporative Emission System Leak Detected (small leak)
 

Has anybody ever had to deal with this. Code is P0442. Before I do any serious debug, hoping someone else went through the pain. Happened when I took off the air filter box to repair the windshield washer pump. All connector are fine.

I'm living through it right now!
 

Maybe you jostled the purge valve or knocked a hose loose?

Re: I'm living through it right now!
 

Have you solved your problem? I reset the code and re-tightened the gas cap but will see what happens.

Wash your gas cap in a solvent (gas)... maybe just a dirty check valve...
 

Take the gasket/O-ring off and clean that area too. I used to get these on occassion but have gone at least a year without now. Keep in mind there are lot of places for potential leaks. That why diagnosing these can be a hassle.

second on that, both times just took off an re-tightened.

Newp...still working on it.

I have had the P0442 code for a while, and I have replaced the gas cap and done a visual/listening inspection of the vacuum lines. Also cleaned out the EGR valve - which was full of carbon (unrelated I know). Also changed out the MAF sensor, and still getting the same code!

Is the best way to do a smoke test to find out the leak? This code is killing me.

Can you explain the gas cap thing? I've had this code for a long time and I just live with it. I found a leaky vacuum line or two, but after resetting the fault, it returns in a few days. When I need to get the car smogged, I just reset the fault before driving it in.

I read that there is a pump in the left rear wheel well, but I have not looked at it.

So...if the gas cap were removed from an A8 that did not have this fault, would the fault then appear?

The leak detection pump is in the left rear fender well, next to top of the shock, behind fender liner.
It's activated by engine vacuum and performs a test of entire fuel system pressure (including tank)right after start up...adds additional pressure. If it fails test (pressure bleeds off too fast), it does a 2nd test...if that fails, it records a fault code.

P.S. The gas cap has a check valve for venting (not to mention normal o-ring seal, when attached correctly). If the valve failed, stuck open, it would be seen as a small leak in the Evap system.