A3 Charcoal Canister Failure
 

I have an 07 Audi A3 3.2L with 81,000 km. Over the summer I found the car would increase from 650RPM idle to about 1100 - 1200 RPM while stopped and remain that way for 20-30 seconds and then go back to normal. Dealer could not diagnose. Now, 4 months later with same symptoms they tell me they think it is the Charcoal Canister has fuel in it... and that the fuel, when it gets in (through overfilling the fuel tank) can never be released, so the problem will never go away. They have told me if the tank was ever overfilled it could have gone in there and will cause this and it WILL NOT be covered under warranty.

Can anyone advise? Is there ANY other way fuel can get into the canister? What else would cause the sporadic and temporary increase in RPM?

Bill

Re: A3 Charcoal Canister Failure
 

This is a problem which can occur in any newer car.

Whenever possible I pump my own gas. If there's an attendant doing the pumping I stand beside them and ask them not to "top up" the tank after the pump automatically shuts off. Squeezing an extra litre or two into the tank to bring it up to an even $ amount can cause you all kinds of grief.

Bill

Re: A3 Charcoal Canister Failure
 

My name is Dave (U/N: Lariam) and I just created an account, so I might mess up as I go through the learning process. This may not be the right thread so pls excuse my ignorance while I share my very recent experience. I have a 2005 A6 (US model) and I have had this car since 2010 and messed around with it somewhat. What I recently learned regarding my code P2404 is that it is not easy to diagnose despite having a mechanic tell me it was the LDP (Leak Detection Pump) and it wasn't. So for me, the code finally cleared itself after I cleaned the charcoal Canister. After reading (a lot) I decided to clean it with water and it worked (for me).......but getting the water out/dried was very time consuming (over the course of 5 days). I ran hot water through the canister in my laundry sink and then went outside an used the garden hose in all 3 lines. Yes a lot of black stuff come out. Between the air compressor, hair dryer and the sun I could finally blow through the inlet (the smallest port) will much less resistance than when I first attempted this. Here in Ontario a brand new one from Audi is 495.00 plus tax....so not cheap. This was my last resort as I had already replaced the purge valve, the LDP and gas cap. If anyone has any questions, I will be happy to answer whatever I can.