Gas mileage problem?

I have a 2000 NB and recently have been experiencing lower gas mileage. I haven't done an accurate check, but I'd say I'm running a little below 20 mpg, almost all highway driving. Any ideas on what my problem could be? I thought maybe sparkplugs as it occasionally idles funny, but there's only 40k miles on it. Thanks for any info.

Just to add, there have been no modifications to the car, automatic transmission.

There's several common problems that will affect gas mileage. Is your check engine light on?

There's several common problems that will affect gas mileage. Is your check engine light on?

Yes, the check engine light is on, but it is also ALWAYS on, even after I've taken it in to be fixed before. I've now started to notice a "chugging" when the car idles. Not always, about half the time. I checked and I'm only getting around 17 mpg.

It's almost guaranteed to be the MAF (mass air flow sensor), you should fall under the extended 7year/70K mile warranty. If not they are easy to install and widely available on the internet. You may want to have the codes read.

I had the same thing happen to me along with many other problems for my 99'. boschmann is right, they had to change my mass air flow sensor. It got better, but I don't think it is as good as it should be.

I found this site w/ mass air flow sensor for $42:
http://tinyurl.com/5kcya

I have the 00 2.0L, so my question is is this really what I want? I'm just curious considering the part for the diesel engine is so much more and when I talked to a vw parts guy here in Seattle he said they probably run around a couple hundred. Input? BTW, my plan from here is to get a diagnostic, but if this part is what I want and is a lot cheaper than the one a mechanic gets to supply this. Thanks.

Unless you have the codes checked you cannot be certain. Often checking the codes is ambiguous, as it won't say MAF bad. More commonly it gets out of calibration & you need a scanner that can read the data measuring blocks, like a VAG-COM simulator, which can be interpreted by someone knowledgable in VW's. The MAF is something you can probably replace yourself & since their price has dropped on the 2.0 it can cost less to just replace it than to have it diagnosed. The only problem is that you will probably need a scanner to reset the light anyway.

So your saying that the price from the link I found is accurate? And thanks for the replies, I really appreciate it.

I haven't dealt witht that company, but the price seems good. My local VW gets about $69 for one now.