Hi, I have a 2004 A4 3.0L Quattro Avant. I live in California.

Recently the Check Engine Light has been on. I have to get a Star Certified Smog Check soon.
I reset the codes/monitors and 7 of the 8 are ready, the only one that is not is the Catalyst Monitor. I've driven in various conditions for over 300 miles the past 2 weeks and it's still not ready (CEL is still off, which is good).

I read somewhere that 2001 and newer cars can have 1 monitor not ready and still be able to pass the smog check, is that true? And if it's true, does that apply for a Star Certified Smog Check station as well?

How can I get it this last monitor to complete the drive cycle and have all 8 monitors ready?

Any help would be much appreciated. Thanks!

 

Hi I have a 2003 TT 1.8T that has catalyst monitor that is not ready. I also live in CA. No CEL has come on that I can remember. I am considering detaching the battery to hard reset all monitors but not sure if that makes a difference or is a viable solution? Driving around to get it ready does not seem to be working.

 

Well, people on this forum were not very helpful, as no one responded. I did figure it out by posting messages on another forum. Don't do the detach battery thing.

You said now CEL has come on that you remember, but it's on NOW I presume?

Get a OBDII scanner and reset all the codes, I think there's 8 of them, it will turn off the CEL for now. Then drive the car around for a few days. people say about 50-75 miles, and check the OBDII scanner once in a while to see which codes are READY OK. The catalyst monitor was the last one of mine to become "ok" and it didn't take 50-75 miles, i drove probably 300+ miles before it actually went to "ready ok" mode and the CEL didn't come back on. I was actually worried that something was wrong and I might have to have an expensive repair. But it finally went off 1 day before my smog check was due! Lucky me. Mechanic wanted $1500 to replace one of the catalytic converters. I just did what i wrote above and didn't spend a dime. 4 months later the CEL still has not come on. I read sometimes there's a faulty switch or something so resetting it like what I did and doing the drive cycle sometimes fixes it.

Good luck, let me know what happens.

 

No CEL now or recently that I recall. Car running beautifully so I am a bit perplexed. I am going to ask mechanic to reset all ready monitors as you have suggested and drive it around all day. Thank you for response.

 

The car should run fine with the Catalyst monitor not set, as long as the front O2 sensors are working. The problem is that the rear O2 sensors following the Cats don't sense enough reduction in Oxygen, which is usually because they (one post-cat sensor in the case of the 1.8T) are not working like they should.