I have a 2000 Audi A4 1.8T with about 130k miles.
Lately it has been giving me about 18-20MPG.
I remember that a few months ago the engine light came on and my mechanic told me that I had a problem with the catalytic converter, but the light went off after a week or so (it's been a while, so I don't have the code).
I was told that an old cat would make my car lose power and start using a lot of gas. Since the light went away I didn't pay much attention to it, even though I bought a new cat (but haven't replaced it, yet).
Would this be the reason I'm getting such MPG?
Any other ideas or things to check for?

I will really appreciate any help!
Thanks!

 

I'd say a bad CAT could definately be to blame. Seeing as you have a new one already then get it on and recheck your MPG. If it still looks low you can start ticking off the million other reasons for a low MPG.

 

clean your maf sensor

 

You are aware that a catalytic converter change requires installation by certified persons, and a sticker reflecting that must be attached to the vehicle, either under the hood or in the door jam, right?

You can't just do it yourself without huge legal problems, should you get caught (which you will next time you have to get emissions checked).

Just a word to the wise.....

 

if you have the stock MAF still with 130k miles on it, just replace it. if you have never replaced the primary O2 sensor, do that as well. if you are getting a "catalyst below efficiency" code, you could have a clogged cat which would rob you of power and MPG.

i dont know where you are located, but no where in the states that i know if is that true, even in california. the only restrictions on cats is you can not buy/sell used ones. no one would ever know who did the work, or even that work had been done. even if you failled your emissions test, they would only tell you that you failed not call the police.

 

.......

 

^ seriously?? proof?

 

yeah hahah proof my ***