Hey guys,

I just bought a 2003 Audi A4 3.0 Quattro. I got it with the fuel cap light flashing because the dealership I had look at it told me that was cause by a bad fuel purge valve which needed replacing and that would only cost $300 to replace. I just got the fuel purge valve replaced today by my mechanic for less then the dealership was charging but it didn't turn off the flashing open fuel cap indicator on the consol.

After looking around I see that this is a fairly common problem and is generally cause by a bad sensor on the fuel tanks neck that determines if the gas cap is on or not. Now before I go and pay for this sensor to be replaced (which will probably be a little more then the purge valve was) I was wondering if having a 3rd party gas cap on there would cause the issue? I know people say only use factory gas caps, I'm guessing because the sensor reads a magnet in the factory gas cap. Anyone have pictures of what the Audi gas caps look like? I'll take a picture of my gas cap later to show you guys.

What do you think? Could it simply be a 3rd party gas cap? Or is it the sensor on the filler neck? Could it be anything else? Any other people here familar with this issue? There's no recall that would save me some money on this is there?

Thanks,
- BoostHungry

PS. Yes I know my name is BoostHungry and I bought a NA 3.0 car. I used to drive a dodge stealth twin turbo and BoostHungry has always been my name since.

 

Yes, you need to have an audi OEM gas cap. Just get it from the dealer, is like 40 bucks.

 

After looking at some pictures that I found which I think are OEM gas caps I think mine is factory. Here are some pictures of my gas cap. It says made in Germany and has the VW symbol on it. Can someone confirm that is the normal gas cap?

 

Looks right, its got the hooks for hanging it on the filler door too.

 

That's the right cap. They do go bad sometimes, there's like a little magnet or something in it tha sometimes comes loose or breaks when the cap falls. You got two options left: Replace your current cap with a new one, or replace the sensor at the fuel filler neck.

 

Hmmm, the guy I got it from said he already replaced the cap so this is a new cap. I guess I gotta replace the sensor. Thanks guys I'll let you know how that goes.

 

Good luck, that little thing can be annoying.

 

Anyone have the part number for that sensor? The mechanic tried telling me, "No there is no sensor like that it simply measures the pressure...blah blah blah". I had to tell him I was positive there is a sensor that uses a magnet to see if the gas cap is on. I've always trusted these guys and they charge very fairly but their respect almost just went out the window with the way the guy was telling me that sensor doesn't exist....I wish I had a lift in my garage and I'd never go to a mechanic again, I just hate working on the floor or on jacks.

Also I read somewhere that a dealership told a guy to simply cut the wire to the sensor and you'll never see that warning again. I'd almost be okay with that but what do you guys think? Am I just going to have to replace this sensor again down the road? Where is access to the wires for the sensor? Would I still have to drop the fuel tank a bit to get to them?

 

Where exactly is this sensor? I pulled down the wheel well matting a bit and had a look around and saw no obvious signs of an electrical sensor, just a lot of tubes for venting and such.

The only thing I felt that seemed like 2 wires were on the top of the filler neck that seemed to attach to the very top, right up against the outside. If I put my finger on what felt like soldered connections for the wires my finger was touching the rubber that surrounds the filler hole right above it. Here:

Does that look about the right place for the sensor? Are those definitely the wires to the sensor?

Oh and I went out and bought some little magnets and tried placing them around the gas cap in all sorts of locations to see if I could get the sensor to pick up the magnets. I had no luck getting the flashing light to stop by using magnets.

 

I looked and I couldn't find it on VAGcat, call the dealer they might know, just tell them that you need the part number for the sensor @ the fuel filler neck. Unless someone else finds it on here.